Re: [Cal_Boats] Prop question - Joe

Joe, Can you tell from the boat speed vs RPM if I have the correct prop on there now? - 1500 - 5.7kt - 1250 - 4.9kt - 1000 - 3.6kt - 750 - 2.4kt Allen On Fri, Feb 24, 2012 at 9:36 AM, Joe DeMers <je… [at] mindspring.com> wrote: > ** > > > ** 14 x 8, 2 blade, RH. If you increase the pitch 1", the rpm will drop > by 200 . [ the engine will then make 2000 rpm ] . Your boat speed is > restricted to 7 knots under power, according to your LWL dimension. > > You will need to run the engine close to maximum rpm to get that > theoretical 7 knots. > > Thanks Allen, for the comments concerning my repowering article. I would > like to write another, but on what subject? > _*/*) > *Joe DeMers - owner* > > Sound Marine Diesel LLC > SoundMarineDiesel.com <http://www.soundmarinediesel.com/> > > *phone & fax (860) 666-2184* > > > > On 2/24/2012 12:10 PM, Allen Edwards wrote: > > > > Thanks Joe, > > The L-36 has a designed LWL of 28 feet. I have not measured the actual. > The engine HP is 31 @ 2200 RPM but I have been told to run it closer to > 1200-1300 RPM. Design weight is 12000 pounds. The gearbox is 1:1. The > boat specification is 14 inch prop and that is what is on there now so I > want to stick with that size. It is also larger than the 13RH9 3 blade I > took off the boat. I want a folding prop, likely a 2 blade non-geared > Martec. > > Allen > > PS. I see lots of hits to your article on my web site. If you ever > write another I would love to post it. > > > On Fri, Feb 24, 2012 at 8:53 AM, Joe DeMers <je… [at] mindspring.com>wrote: > > > > Start here - > > max diameter prop that will fit the boat. > > Load waterline of hull > > engine hp @ what? rpm > > reduction gear ratio. > > > > Send that info, and I will get you a prop recommendation. > > _* / * ) > * Joe DeMers - owner * > > Sound Marine Diesel LLC > SoundMarineDiesel.com <http://www.soundmarinediesel.com/> > > * phone & fax (860) 666-2184 <%28860%29%20666-2184> * > > > On 2/24/2012 11:32 AM, Allen Edwards wrote: > > > I am facing a decision on my prop. As part of getting my Grey Marine > 4-112 rebuilt I need to also do something with the old Martec folding prop > as my diver says it needs servicing, which I have never done. I need to > decide repair or replace on the prop. One of the questions I have is do I > have the best size prop. Without actually knowing what size the existing > prop is, this is really a difficult question but I do have a fair amount of > information. Here is what I know: > > - Lapworth specified 14RH8 on the blueprint for the L-36 > - The 3 blade that was on the boat when I got it was a 13RH9 > - I removed the 3 blade and installed the Martec folding that was in > the lazarette. > - I dove to measure the prop and it measured 14 inches with an angle > at 2/3 or the way out of 11-16 degrees which would mean a pitch in the 6 to > 8 range. Not that close a measurement I know. > - The Grey Marine Engine manual suggests 14x9 or 13x10 for that size > engine (no mention of boat size or power vs sail) > - Engine vs Boat Speed with existing prop: > - 1500 - 5.7kt > - 1250 - 4.9kt > - 1000 - 3.6kt > - 750 - 2.4kt > - The above measurements were taken with my old worn out engine which > has 40 psi compression. It ran fine. > - I have a vague memory of seeing a graph my dad did showing the boat > was faster at any given RPM with the fixed blade. > - Cruising RPM per my mechanic is around 1300 > - Maximum HP 31@2200RPM per engine manual > - Repair prop $210 + shipping ($30) + labor ? ($70) = $310ish > - New Prop of newer design $710 + shipping + labor? = $750ish > - I put 30 hrs a year on the engine, basically only race or go to > races. I just say this to point out I need a low drag prop. > > Rebuilding is cheaper but if I am told the more modern design backs up > better, whatever that means. There is no way I could back up worse as I > can't back up at all. All reverse is good for is stopping the boat and > does that well with no problems. I blame the offset prop that sits above > the rudder so there is no backwash against the rudder for the backing > problems although I am told that isn't correct, another story. > > The other question is, with the information above, do I have the right > prop on the boat now? If I can get better performance with a new prop, > this would be the time to get it. There are basically two ways that it > might be worth getting a new prop > > - Better backing which I have to take either on faith or from > testimonial from one of you > - Better boat speed because the results above indicate I have the > wrong prop pitch > > Any thoughts? Joe??? Others??? > > Allen > > No virus found in this message. > Checked by AVG - www.avg.com > Version: 2012.0.1913 / Virus Database: 2114/4829 - Release Date: 02/24/12 > > > -- > > * Joe DeMers - owner * > > Sound Marine Diesel LLC > SoundMarineDiesel.com <http://www.soundmarinediesel.com/> > > * phone & fax (860) 666-2184 <%28860%29%20666-2184> * > > > > > No virus found in this message. > Checked by AVG - www.avg.com > Version: 2012.0.1913 / Virus Database: 2114/4829 - Release Date: 02/24/12 > > > -- > > *Joe DeMers - owner* > > Sound Marine Diesel LLC > SoundMarineDiesel.com <http://www.soundmarinediesel.com/> > > *phone & fax (860) 666-2184* > > >

I would first check the accuracy of your tach, using a laser tachometer. Then run the engine at 2200 rpm and note the boat speed. Joe On 2/24/2012 5:48 PM, Allen Edwards wrote: > > > Joe, > > Can you tell from the boat speed vs RPM if I have the correct prop on > there now? > > * 1500 - 5.7kt > * 1250 - 4.9kt > * 1000 - 3.6kt > * 750 - 2.4kt > > Allen > > > On Fri, Feb 24, 2012 at 9:36 AM, Joe DeMers <je… [at] mindspring.com > <mailto:je… [at] mindspring.com>> wrote: > > 14 x 8, 2 blade, RH. If you increase the pitch 1", the rpm will > drop by 200 . [ the engine will then make 2000 rpm ] . Your boat > speed is restricted to 7 knots under power, according to your LWL > dimension. > > You will need to run the engine close to maximum rpm to get that > theoretical 7 knots. > > Thanks Allen, for the comments concerning my repowering article. > I would like to write another, but on what subject? > > _*/*) > *Joe DeMers - owner* > > Sound Marine Diesel LLC > > SoundMarineDiesel.com <http://www.soundmarinediesel.com/> > > *phone & fax (860) 666-2184 <tel:%28860%29%20666-2184>* > > > > > On 2/24/2012 12:10 PM, Allen Edwards wrote: >> >> >> Thanks Joe, >> >> The L-36 has a designed LWL of 28 feet. I have not measured the >> actual. The engine HP is 31 @ 2200 RPM but I have been told to >> run it closer to 1200-1300 RPM. Design weight is 12000 pounds. >> The gearbox is 1:1. The boat specification is 14 inch prop and >> that is what is on there now so I want to stick with that size. >> It is also larger than the 13RH9 3 blade I took off the boat. I >> want a folding prop, likely a 2 blade non-geared Martec. >> >> Allen >> >> PS. I see lots of hits to your article on my web site. If you >> ever write another I would love to post it. >> >> >> On Fri, Feb 24, 2012 at 8:53 AM, Joe DeMers >> <je… [at] mindspring.com <mailto:je… [at] mindspring.com>> wrote: >> >> Start here - >> >> max diameter prop that will fit the boat. >> >> Load waterline of hull >> >> engine hp @ what? rpm >> >> reduction gear ratio. >> >> >> >> Send that info, and I will get you a prop recommendation. >> >> _*/ * ) >> >> *Joe DeMers - owner * >> >> Sound Marine Diesel LLC >> >> SoundMarineDiesel.com <http://www.soundmarinediesel.com/> >> >> *phone & fax (860) 666-2184 <tel:%28860%29%20666-2184> * >> >> >> >> On 2/24/2012 11:32 AM, Allen Edwards wrote: >>> >>> I am facing a decision on my prop. As part of getting my >>> Grey Marine 4-112 rebuilt I need to also do something with >>> the old Martec folding prop as my diver says it needs >>> servicing, which I have never done. I need to decide repair >>> or replace on the prop. One of the questions I have is do I >>> have the best size prop. Without actually knowing what size >>> the existing prop is, this is really a difficult question >>> but I do have a fair amount of information. Here is what I >>> know: >>> >>> * Lapworth specified 14RH8 on the blueprint for the L-36 >>> * The 3 blade that was on the boat when I got it was a 13RH9 >>> * I removed the 3 blade and installed the Martec folding >>> that was in the lazarette. >>> * I dove to measure the prop and it measured 14 inches >>> with an angle at 2/3 or the way out of 11-16 degrees >>> which would mean a pitch in the 6 to 8 range. Not >>> that close a measurement I know. >>> * The Grey Marine Engine manual suggests 14x9 or 13x10 >>> for that size engine (no mention of boat size or power >>> vs sail) >>> * Engine vs Boat Speed with existing prop: >>> * 1500 - 5.7kt >>> * 1250 - 4.9kt >>> * 1000 - 3.6kt >>> * 750 - 2.4kt >>> * The above measurements were taken with my old worn out >>> engine which has 40 psi compression. It ran fine. >>> * I have a vague memory of seeing a graph my dad did >>> showing the boat was faster at any given RPM with the >>> fixed blade. >>> * Cruising RPM per my mechanic is around 1300 >>> * Maximum HP 31@2200RPM per engine manual >>> * Repair prop $210 + shipping ($30) + labor ? ($70) = >>> $310ish >>> * New Prop of newer design $710 + shipping + labor? = >>> $750ish >>> * I put 30 hrs a year on the engine, basically only race >>> or go to races. I just say this to point out I need a >>> low drag prop. >>> >>> Rebuilding is cheaper but if I am told the more modern >>> design backs up better, whatever that means. There is no >>> way I could back up worse as I can't back up at all. All >>> reverse is good for is stopping the boat and does that well >>> with no problems. I blame the offset prop that sits above >>> the rudder so there is no backwash against the rudder for >>> the backing problems although I am told that isn't correct, >>> another story. >>> >>> The other question is, with the information above, do I have >>> the right prop on the boat now? If I can get better >>> performance with a new prop, this would be the time to get >>> it. There are basically two ways that it might be worth >>> getting a new prop >>> >>> * Better backing which I have to take either on faith or >>> from testimonial from one of you >>> * Better boat speed because the results above indicate I >>> have the wrong prop pitch >>> >>> Any thoughts? Joe??? Others??? >>> >>> Allen >>> >>> No virus found in this message. >>> Checked by AVG - www.avg.com <http://www.avg.com> >>> Version: 2012.0.1913 / Virus Database: 2114/4829 - Release >>> Date: 02/24/12 >>> >> >> -- >> >> *Joe DeMers - owner * >> >> Sound Marine Diesel LLC >> >> SoundMarineDiesel.com <http://www.soundmarinediesel.com/> >> >> *phone & fax (860) 666-2184 <tel:%28860%29%20666-2184> * >> >> >> >> >> No virus found in this message. >> Checked by AVG - www.avg.com <http://www.avg.com> >> Version: 2012.0.1913 / Virus Database: 2114/4829 - Release Date: >> 02/24/12 >> > > -- > > *Joe DeMers - owner* > > Sound Marine Diesel LLC > > SoundMarineDiesel.com <http://www.soundmarinediesel.com/> > > *phone & fax (860) 666-2184 <tel:%28860%29%20666-2184>* > > > > > > > No virus found in this message. > Checked by AVG - www.avg.com <http://www.avg.com> > Version: 2012.0.1913 / Virus Database: 2114/4829 - Release Date: 02/24/12 > -- *Joe DeMers - owner* Sound Marine Diesel LLC SoundMarineDiesel.com <http://www.soundmarinediesel.com/> *phone & fax (860) 666-2184*

The tach is mechanical and old so you have a good point that it might be off. With the engine 56 years old I just need it to run another 2 hours so running it at full rated revs isn't happening before the rebuild. The engine guy is Dave Van Ness web site<http://www.vannessengineering.com/> and I believe he told me that the operating range was 1200-1300 RPM so I don't even know for sure 2200 is in the cards even after the rebuild although 2200 doesn't sound very high for an engine. So we have a chicken and egg thing here. Need the new engine to test the prop and need to prob before the new engine. What to do??? Allen On Sat, Feb 25, 2012 at 6:26 PM, Joe DeMers <je… [at] mindspring.com> wrote: > ** > > > ** I would first check the accuracy of your tach, using a laser > tachometer. > > Then run the engine at 2200 rpm and note the boat speed. > Joe > > > On 2/24/2012 5:48 PM, Allen Edwards wrote: > > Joe, > > Can you tell from the boat speed vs RPM if I have the correct prop on > there now? > > - 1500 - 5.7kt > - 1250 - 4.9kt > - 1000 - 3.6kt > - 750 - 2.4kt > > Allen > > > On Fri, Feb 24, 2012 at 9:36 AM, Joe DeMers <je… [at] mindspring.com>wrote: > >> >> >> 14 x 8, 2 blade, RH. If you increase the pitch 1", the rpm will drop by >> 200 . [ the engine will then make 2000 rpm ] . Your boat speed is >> restricted to 7 knots under power, according to your LWL dimension. >> >> You will need to run the engine close to maximum rpm to get that >> theoretical 7 knots. >> >> Thanks Allen, for the comments concerning my repowering article. I would >> like to write another, but on what subject? >> _*/*) >> *Joe DeMers - owner* >> >> Sound Marine Diesel LLC >> SoundMarineDiesel.com <http://www.soundmarinediesel.com/> >> >> *phone & fax (860) 666-2184 <%28860%29%20666-2184>* >> >> >> >> On 2/24/2012 12:10 PM, Allen Edwards wrote: >> >> >> >> Thanks Joe, >> >> The L-36 has a designed LWL of 28 feet. I have not measured the actual. >> The engine HP is 31 @ 2200 RPM but I have been told to run it closer to >> 1200-1300 RPM. Design weight is 12000 pounds. The gearbox is 1:1. The >> boat specification is 14 inch prop and that is what is on there now so I >> want to stick with that size. It is also larger than the 13RH9 3 blade I >> took off the boat. I want a folding prop, likely a 2 blade non-geared >> Martec. >> >> Allen >> >> PS. I see lots of hits to your article on my web site. If you ever >> write another I would love to post it. >> >> >> On Fri, Feb 24, 2012 at 8:53 AM, Joe DeMers <je… [at] mindspring.com>wrote: >> >> >> >> Start here - >> >> max diameter prop that will fit the boat. >> >> Load waterline of hull >> >> engine hp @ what? rpm >> >> reduction gear ratio. >> >> >> >> Send that info, and I will get you a prop recommendation. >> >> _* / * ) >> * Joe DeMers - owner * >> >> Sound Marine Diesel LLC >> SoundMarineDiesel.com <http://www.soundmarinediesel.com/> >> >> * phone & fax (860) 666-2184 <%28860%29%20666-2184> * >> >> >> On 2/24/2012 11:32 AM, Allen Edwards wrote: >> >> >> I am facing a decision on my prop. As part of getting my Grey Marine >> 4-112 rebuilt I need to also do something with the old Martec folding prop >> as my diver says it needs servicing, which I have never done. I need to >> decide repair or replace on the prop. One of the questions I have is do I >> have the best size prop. Without actually knowing what size the existing >> prop is, this is really a difficult question but I do have a fair amount of >> information. Here is what I know: >> >> - Lapworth specified 14RH8 on the blueprint for the L-36 >> - The 3 blade that was on the boat when I got it was a 13RH9 >> - I removed the 3 blade and installed the Martec folding that was in >> the lazarette. >> - I dove to measure the prop and it measured 14 inches with an angle >> at 2/3 or the way out of 11-16 degrees which would mean a pitch in the 6 to >> 8 range. Not that close a measurement I know. >> - The Grey Marine Engine manual suggests 14x9 or 13x10 for that size >> engine (no mention of boat size or power vs sail) >> - Engine vs Boat Speed with existing prop: >> - 1500 - 5.7kt >> - 1250 - 4.9kt >> - 1000 - 3.6kt >> - 750 - 2.4kt >> - The above measurements were taken with my old worn out engine which >> has 40 psi compression. It ran fine. >> - I have a vague memory of seeing a graph my dad did showing the boat >> was faster at any given RPM with the fixed blade. >> - Cruising RPM per my mechanic is around 1300 >> - Maximum HP 31@2200RPM per engine manual >> - Repair prop $210 + shipping ($30) + labor ? ($70) = $310ish >> - New Prop of newer design $710 + shipping + labor? = $750ish >> - I put 30 hrs a year on the engine, basically only race or go to >> races. I just say this to point out I need a low drag prop. >> >> Rebuilding is cheaper but if I am told the more modern design backs up >> better, whatever that means. There is no way I could back up worse as I >> can't back up at all. All reverse is good for is stopping the boat and >> does that well with no problems. I blame the offset prop that sits above >> the rudder so there is no backwash against the rudder for the backing >> problems although I am told that isn't correct, another story. >> >> The other question is, with the information above, do I have the right >> prop on the boat now? If I can get better performance with a new prop, >> this would be the time to get it. There are basically two ways that it >> might be worth getting a new prop >> >> - Better backing which I have to take either on faith or from >> testimonial from one of you >> - Better boat speed because the results above indicate I have the >> wrong prop pitch >> >> Any thoughts? Joe??? Others??? >> >> Allen >> >> No virus found in this message. >> Checked by AVG - www.avg.com >> Version: 2012.0.1913 / Virus Database: 2114/4829 - Release Date: 02/24/12 >> >> >> -- >> >> * Joe DeMers - owner * >> >> Sound Marine Diesel LLC >> SoundMarineDiesel.com <http://www.soundmarinediesel.com/> >> >> * phone & fax (860) 666-2184 <%28860%29%20666-2184> * >> >> >> >> >> No virus found in this message. >> Checked by AVG - www.avg.com >> Version: 2012.0.1913 / Virus Database: 2114/4829 - Release Date: 02/24/12 >> >> >> -- >> >> *Joe DeMers - owner* >> >> Sound Marine Diesel LLC >> SoundMarineDiesel.com <http://www.soundmarinediesel.com/> >> >> *phone & fax (860) 666-2184 <%28860%29%20666-2184>* >> > > No virus found in this message. > Checked by AVG - www.avg.com > Version: 2012.0.1913 / Virus Database: 2114/4829 - Release Date: 02/24/12 > > > -- > > *Joe DeMers - owner* > > Sound Marine Diesel LLC > SoundMarineDiesel.com <http://www.soundmarinediesel.com/> > > *phone & fax (860) 666-2184* > > >

On 2/25/2012 11:50 PM, Allen Edwards wrote: > > > > The tach is mechanical and old so you have a good point that it might > be off. With the engine 56 years old I just need it to run another 2 > hours so running it at full rated revs isn't happening before the rebuild. > > The engine guy is Dave Van Ness web site > <http://www.vannessengineering.com/> and I believe he told me that the > operating range was 1200-1300 RPM so I don't even know for sure 2200 > is in the cards even after the rebuild although 2200 doesn't sound > very high for an engine. > > So we have a chicken and egg thing here. Need the new engine to test > the prop and need to prob before the new engine. > > What to do??? ********* Try the recommended prop after the engine rebuild. *Joe DeMers - owner* Sound Marine Diesel LLC SoundMarineDiesel.com <http://www.soundmarinediesel.com/> *phone & fax (860) 666-2184* > > Allen > > > > On Sat, Feb 25, 2012 at 6:26 PM, Joe DeMers <je… [at] mindspring.com > <mailto:je… [at] mindspring.com>> wrote: > > I would first check the accuracy of your tach, using a laser > tachometer. > > Then run the engine at 2200 rpm and note the boat speed. > Joe > > > > On 2/24/2012 5:48 PM, Allen Edwards wrote: >> Joe, >> >> Can you tell from the boat speed vs RPM if I have the correct >> prop on there now? >> >> * 1500 - 5.7kt >> * 1250 - 4.9kt >> * 1000 - 3.6kt >> * 750 - 2.4kt >> >> Allen >> >> >> On Fri, Feb 24, 2012 at 9:36 AM, Joe DeMers >> <je… [at] mindspring.com <mailto:je… [at] mindspring.com>> wrote: >> >> 14 x 8, 2 blade, RH. If you increase the pitch 1", the rpm >> will drop by 200 . [ the engine will then make 2000 rpm ] . >> Your boat speed is restricted to 7 knots under power, >> according to your LWL dimension. >> >> You will need to run the engine close to maximum rpm to get >> that theoretical 7 knots. >> >> Thanks Allen, for the comments concerning my repowering >> article. I would like to write another, but on what subject? >> >> _*/ * ) >> *Joe DeMers - owner * >> >> Sound Marine Diesel LLC >> >> SoundMarineDiesel.com <http://www.soundmarinediesel.com/> >> >> *phone & fax (860) 666-2184 <tel:%28860%29%20666-2184> * >> >> >> >> >> On 2/24/2012 12:10 PM, Allen Edwards wrote: >>> >>> >>> Thanks Joe, >>> >>> The L-36 has a designed LWL of 28 feet. I have not measured >>> the actual. The engine HP is 31 @ 2200 RPM but I have been >>> told to run it closer to 1200-1300 RPM. Design weight is >>> 12000 pounds. The gearbox is 1:1. The boat specification >>> is 14 inch prop and that is what is on there now so I want >>> to stick with that size. It is also larger than the 13RH9 3 >>> blade I took off the boat. I want a folding prop, likely a >>> 2 blade non-geared Martec. >>> >>> Allen >>> >>> PS. I see lots of hits to your article on my web site. If >>> you ever write another I would love to post it. >>> >>> >>> On Fri, Feb 24, 2012 at 8:53 AM, Joe DeMers >>> <je… [at] mindspring.com <mailto:je… [at] mindspring.com>> wrote: >>> >>> Start here - >>> >>> max diameter prop that will fit the boat. >>> >>> Load waterline of hull >>> >>> engine hp @ what? rpm >>> >>> reduction gear ratio. >>> >>> >>> >>> Send that info, and I will get you a prop recommendation. >>> >>> _*/ * ) >>> >>> *Joe DeMers - owner * >>> >>> Sound Marine Diesel LLC >>> >>> SoundMarineDiesel.com <http://www.soundmarinediesel.com/> >>> >>> *phone & fax (860) 666-2184 <tel:%28860%29%20666-2184> * >>> >>> >>> >>> On 2/24/2012 11:32 AM, Allen Edwards wrote: >>>> >>>> I am facing a decision on my prop. As part of getting >>>> my Grey Marine 4-112 rebuilt I need to also do >>>> something with the old Martec folding prop as my diver >>>> says it needs servicing, which I have never done. I >>>> need to decide repair or replace on the prop. One of >>>> the questions I have is do I have the best size prop. >>>> Without actually knowing what size the existing prop >>>> is, this is really a difficult question but I do have a >>>> fair amount of information. Here is what I know: >>>> >>>> * Lapworth specified 14RH8 on the blueprint for the >>>> L-36 >>>> * The 3 blade that was on the boat when I got it >>>> was a 13RH9 >>>> * I removed the 3 blade and installed the Martec >>>> folding that was in the lazarette. >>>> * I dove to measure the prop and it measured 14 >>>> inches with an angle at 2/3 or the way out of >>>> 11-16 degrees which would mean a pitch in the 6 >>>> to 8 range. Not that close a measurement I know. >>>> * The Grey Marine Engine manual suggests 14x9 or >>>> 13x10 for that size engine (no mention of boat >>>> size or power vs sail) >>>> * Engine vs Boat Speed with existing prop: >>>> * 1500 - 5.7kt >>>> * 1250 - 4.9kt >>>> * 1000 - 3.6kt >>>> * 750 - 2.4kt >>>> * The above measurements were taken with my old >>>> worn out engine which has 40 psi compression. It >>>> ran fine. >>>> * I have a vague memory of seeing a graph my dad >>>> did showing the boat was faster at any given RPM >>>> with the fixed blade. >>>> * Cruising RPM per my mechanic is around 1300 >>>> * Maximum HP 31@2200RPM per engine manual >>>> * Repair prop $210 + shipping ($30) + labor ? ($70) >>>> = $310ish >>>> * New Prop of newer design $710 + shipping + labor? >>>> = $750ish >>>> * I put 30 hrs a year on the engine, basically only >>>> race or go to races. I just say this to point >>>> out I need a low drag prop. >>>> >>>> Rebuilding is cheaper but if I am told the more modern >>>> design backs up better, whatever that means. There is >>>> no way I could back up worse as I can't back up at all. >>>> All reverse is good for is stopping the boat and does >>>> that well with no problems. I blame the offset prop >>>> that sits above the rudder so there is no backwash >>>> against the rudder for the backing problems although I >>>> am told that isn't correct, another story. >>>> >>>> The other question is, with the information above, do I >>>> have the right prop on the boat now? If I can get >>>> better performance with a new prop, this would be the >>>> time to get it. There are basically two ways that it >>>> might be worth getting a new prop >>>> >>>> * Better backing which I have to take either on >>>> faith or from testimonial from one of you >>>> * Better boat speed because the results above >>>> indicate I have the wrong prop pitch >>>> >>>> Any thoughts? Joe??? Others??? >>>> >>>> Allen >>>> >>>> No virus found in this message. >>>> Checked by AVG - www.avg.com <http://www.avg.com> >>>> Version: 2012.0.1913 / Virus Database: 2114/4829 - >>>> Release Date: 02/24/12 >>>> >>> >>> -- >>> >>> *Joe DeMers - owner * >>> >>> Sound Marine Diesel LLC >>> >>> SoundMarineDiesel.com <http://www.soundmarinediesel.com/> >>> >>> *phone & fax (860) 666-2184 <tel:%28860%29%20666-2184> * >>> >>> >>> >>> >>> No virus found in this message. >>> Checked by AVG - www.avg.com <http://www.avg.com> >>> Version: 2012.0.1913 / Virus Database: 2114/4829 - Release >>> Date: 02/24/12 >>> >> >> -- >> >> *Joe DeMers - owner * >> >> Sound Marine Diesel LLC >> >> SoundMarineDiesel.com <http://www.soundmarinediesel.com/> >> >> *phone & fax (860) 666-2184 <tel:%28860%29%20666-2184> * >> >> >> No virus found in this message. >> Checked by AVG - www.avg.com <http://www.avg.com> >> Version: 2012.0.1913 / Virus Database: 2114/4829 - Release Date: >> 02/24/12 >> > > -- > > *Joe DeMers - owner * > > Sound Marine Diesel LLC > > SoundMarineDiesel.com <http://www.soundmarinediesel.com/> > > *phone & fax (860) 666-2184 <tel:%28860%29%20666-2184> * > > > > > > > No virus found in this message. > Checked by AVG - www.avg.com <http://www.avg.com> > Version: 2012.0.1913 / Virus Database: 2114/4831 - Release Date: 02/25/12 > -- *Joe DeMers - owner* Sound Marine Diesel LLC SoundMarineDiesel.com <http://www.soundmarinediesel.com/> *phone & fax (860) 666-2184*

Joe, The tack reads 60 RPM high. I have a clip on tack on my automotive voltmeter. I have to assume that is correct. I tested from 500 to 1300 RPM and it is pretty much 60 RPM high and not a percentage. That means that I am doing 5.7 kt at 1440RPM. Thanks for raising that issue. I talked to Martec and they felt that I had a 14RH7 as they only made 3 different props back in the old days and that was the one I probably had given that Lapworth specified 14RH8. However, the original engine was 25HP at 2000RPM 91 cubic inch vs mine that is 31HP @ 2200 rpm 112 cubic inch. Apparently my engine is not as old as the boat. The owners at Martec knew my boat. Their dad raced against when they were young. They recommended a 14RH10 and as I am told that the 2 blade Martec folding prop has more slip than a more conventional prop, I felt that was consistent with your recommendation as well. Also, the engine rebuilder, also a sailor, felt that was the correct prop and closer in performance to the three blade 13RH9 that was on the boat when I got it. So, I ordered a new prop. I hope it is the right one. Thanks for your help, Allen On Mon, Feb 27, 2012 at 4:23 AM, Joe DeMers <je… [at] mindspring.com> wrote: > ** > > > ** > > On 2/25/2012 11:50 PM, Allen Edwards wrote: > > > > > The tach is mechanical and old so you have a good point that it might be > off. With the engine 56 years old I just need it to run another 2 hours so > running it at full rated revs isn't happening before the rebuild. > > The engine guy is Dave Van Ness web site<http://www.vannessengineering.com/> and > I believe he told me that the operating range was 1200-1300 RPM so I don't > even know for sure 2200 is in the cards even after the rebuild although > 2200 doesn't sound very high for an engine. > > So we have a chicken and egg thing here. Need the new engine to test > the prop and need to prob before the new engine. > > What to do??? > > > ********* Try the recommended prop after the engine rebuild. > > *Joe DeMers - owner* > > Sound Marine Diesel LLC > SoundMarineDiesel.com <http://www.soundmarinediesel.com/> > > *phone & fax (860) 666-2184* > > > > Allen > > > > On Sat, Feb 25, 2012 at 6:26 PM, Joe DeMers <je… [at] mindspring.com>wrote: > > > > I would first check the accuracy of your tach, using a laser tachometer. > > Then run the engine at 2200 rpm and note the boat speed. > Joe > > > On 2/24/2012 5:48 PM, Allen Edwards wrote: > > Joe, > > Can you tell from the boat speed vs RPM if I have the correct prop on > there now? > > - 1500 - 5.7kt > - 1250 - 4.9kt > - 1000 - 3.6kt > - 750 - 2.4kt > > Allen > > > On Fri, Feb 24, 2012 at 9:36 AM, Joe DeMers <je… [at] mindspring.com>wrote: > > > > 14 x 8, 2 blade, RH. If you increase the pitch 1", the rpm will drop by > 200 . [ the engine will then make 2000 rpm ] . Your boat speed is > restricted to 7 knots under power, according to your LWL dimension. > > You will need to run the engine close to maximum rpm to get that > theoretical 7 knots. > > Thanks Allen, for the comments concerning my repowering article. I would > like to write another, but on what subject? > _* / * ) > * Joe DeMers - owner * > > Sound Marine Diesel LLC > SoundMarineDiesel.com <http://www.soundmarinediesel.com/> > > * phone & fax (860) 666-2184 * > > > > On 2/24/2012 12:10 PM, Allen Edwards wrote: > > > > Thanks Joe, > > The L-36 has a designed LWL of 28 feet. I have not measured the actual. > The engine HP is 31 @ 2200 RPM but I have been told to run it closer to > 1200-1300 RPM. Design weight is 12000 pounds. The gearbox is 1:1. The > boat specification is 14 inch prop and that is what is on there now so I > want to stick with that size. It is also larger than the 13RH9 3 blade I > took off the boat. I want a folding prop, likely a 2 blade non-geared > Martec. > > Allen > > PS. I see lots of hits to your article on my web site. If you ever > write another I would love to post it. > > > On Fri, Feb 24, 2012 at 8:53 AM, Joe DeMers <je… [at] mindspring.com>wrote: > > > > Start here - > > max diameter prop that will fit the boat. > > Load waterline of hull > > engine hp @ what? rpm > > reduction gear ratio. > > > > Send that info, and I will get you a prop recommendation. > > _* / * ) > * Joe DeMers - owner * > > Sound Marine Diesel LLC > SoundMarineDiesel.com <http://www.soundmarinediesel.com/> > > * phone & fax (860) 666-2184 * > > > On 2/24/2012 11:32 AM, Allen Edwards wrote: > > > I am facing a decision on my prop. As part of getting my Grey Marine > 4-112 rebuilt I need to also do something with the old Martec folding prop > as my diver says it needs servicing, which I have never done. I need to > decide repair or replace on the prop. One of the questions I have is do I > have the best size prop. Without actually knowing what size the existing > prop is, this is really a difficult question but I do have a fair amount of > information. Here is what I know: > > - Lapworth specified 14RH8 on the blueprint for the L-36 > - The 3 blade that was on the boat when I got it was a 13RH9 > - I removed the 3 blade and installed the Martec folding that was in > the lazarette. > - I dove to measure the prop and it measured 14 inches with an angle > at 2/3 or the way out of 11-16 degrees which would mean a pitch in the 6 to > 8 range. Not that close a measurement I know. > - The Grey Marine Engine manual suggests 14x9 or 13x10 for that size > engine (no mention of boat size or power vs sail) > - Engine vs Boat Speed with existing prop: > - 1500 - 5.7kt > - 1250 - 4.9kt > - 1000 - 3.6kt > - 750 - 2.4kt > - The above measurements were taken with my old worn out engine which > has 40 psi compression. It ran fine. > - I have a vague memory of seeing a graph my dad did showing the boat > was faster at any given RPM with the fixed blade. > - Cruising RPM per my mechanic is around 1300 > - Maximum HP 31@2200RPM per engine manual > - Repair prop $210 + shipping ($30) + labor ? ($70) = $310ish > - New Prop of newer design $710 + shipping + labor? = $750ish > - I put 30 hrs a year on the engine, basically only race or go to > races. I just say this to point out I need a low drag prop. > > Rebuilding is cheaper but if I am told the more modern design backs up > better, whatever that means. There is no way I could back up worse as I > can't back up at all. All reverse is good for is stopping the boat and > does that well with no problems. I blame the offset prop that sits above > the rudder so there is no backwash against the rudder for the backing > problems although I am told that isn't correct, another story. > > The other question is, with the information above, do I have the right > prop on the boat now? If I can get better performance with a new prop, > this would be the time to get it. There are basically two ways that it > might be worth getting a new prop > > - Better backing which I have to take either on faith or from > testimonial from one of you > - Better boat speed because the results above indicate I have the > wrong prop pitch > > Any thoughts? Joe??? Others??? > > Allen > > No virus found in this message. > Checked by AVG - www.avg.com > Version: 2012.0.1913 / Virus Database: 2114/4829 - Release Date: 02/24/12 > > > -- > > * Joe DeMers - owner * > > Sound Marine Diesel LLC > SoundMarineDiesel.com <http://www.soundmarinediesel.com/> > > * phone & fax (860) 666-2184 * > > > > > No virus found in this message. > Checked by AVG - www.avg.com > Version: 2012.0.1913 / Virus Database: 2114/4829 - Release Date: 02/24/12 > > > -- > > * Joe DeMers - owner * > > Sound Marine Diesel LLC > SoundMarineDiesel.com <http://www.soundmarinediesel.com/> > > * phone & fax (860) 666-2184 * > > > No virus found in this message. > Checked by AVG - www.avg.com > Version: 2012.0.1913 / Virus Database: 2114/4829 - Release Date: 02/24/12 > > > -- > > * Joe DeMers - owner * > > Sound Marine Diesel LLC > SoundMarineDiesel.com <http://www.soundmarinediesel.com/> > > * phone & fax (860) 666-2184 <%28860%29%20666-2184> * > > > > > No virus found in this message. > Checked by AVG - www.avg.com > Version: 2012.0.1913 / Virus Database: 2114/4831 - Release Date: 02/25/12 > > > -- > > *Joe DeMers - owner* > > Sound Marine Diesel LLC > SoundMarineDiesel.com <http://www.soundmarinediesel.com/> > > *phone & fax (860) 666-2184* > > >

Keep us informed - Joe DeMers On 3/6/2012 11:47 PM, Allen Edwards wrote: > > > Joe, > > The tack reads 60 RPM high. I have a clip on tack on my automotive > voltmeter. I have to assume that is correct. I tested from 500 to > 1300 RPM and it is pretty much 60 RPM high and not a percentage. That > means that I am doing 5.7 kt at 1440RPM. Thanks for raising that issue. > > I talked to Martec and they felt that I had a 14RH7 as they only made > 3 different props back in the old days and that was the one I probably > had given that Lapworth specified 14RH8. However, the original engine > was 25HP at 2000RPM 91 cubic inch vs mine that is 31HP @ 2200 rpm 112 > cubic inch. Apparently my engine is not as old as the boat. > > The owners at Martec knew my boat. Their dad raced against when they > were young. They recommended a 14RH10 and as I am told that the 2 > blade Martec folding prop has more slip than a more conventional prop, > I felt that was consistent with your recommendation as well. Also, > the engine rebuilder, also a sailor, felt that was the correct prop > and closer in performance to the three blade 13RH9 that was on the > boat when I got it. > > So, I ordered a new prop. I hope it is the right one. > > Thanks for your help, > > Allen > > > On Mon, Feb 27, 2012 at 4:23 AM, Joe DeMers <je… [at] mindspring.com > <mailto:je… [at] mindspring.com>> wrote: > > > > On 2/25/2012 11:50 PM, Allen Edwards wrote: >> >> >> >> The tach is mechanical and old so you have a good point that it >> might be off. With the engine 56 years old I just need it to run >> another 2 hours so running it at full rated revs isn't happening >> before the rebuild. >> >> The engine guy is Dave Van Ness web site >> <http://www.vannessengineering.com/> and I believe he told me >> that the operating range was 1200-1300 RPM so I don't even know >> for sure 2200 is in the cards even after the rebuild although >> 2200 doesn't sound very high for an engine. >> >> So we have a chicken and egg thing here. Need the new engine to >> test the prop and need to prob before the new engine. >> >> What to do??? > > ********* Try the recommended prop after the engine rebuild. > > *Joe DeMers - owner* > > Sound Marine Diesel LLC > > SoundMarineDiesel.com <http://www.soundmarinediesel.com/> > > *phone & fax (860) 666-2184 <tel:%28860%29%20666-2184>* > > > >> >> Allen >> >> >> >> On Sat, Feb 25, 2012 at 6:26 PM, Joe DeMers >> <je… [at] mindspring.com <mailto:je… [at] mindspring.com>> wrote: >> >> I would first check the accuracy of your tach, using a laser >> tachometer. >> >> Then run the engine at 2200 rpm and note the boat speed. >> Joe >> >> >> >> On 2/24/2012 5:48 PM, Allen Edwards wrote: >>> Joe, >>> >>> Can you tell from the boat speed vs RPM if I have the >>> correct prop on there now? >>> >>> * 1500 - 5.7kt >>> * 1250 - 4.9kt >>> * 1000 - 3.6kt >>> * 750 - 2.4kt >>> >>> Allen >>> >>> >>> On Fri, Feb 24, 2012 at 9:36 AM, Joe DeMers >>> <je… [at] mindspring.com <mailto:je… [at] mindspring.com>> wrote: >>> >>> 14 x 8, 2 blade, RH. If you increase the pitch 1", the >>> rpm will drop by 200 . [ the engine will then make 2000 >>> rpm ] . Your boat speed is restricted to 7 knots under >>> power, according to your LWL dimension. >>> >>> You will need to run the engine close to maximum rpm to >>> get that theoretical 7 knots. >>> >>> Thanks Allen, for the comments concerning my repowering >>> article. I would like to write another, but on what >>> subject? >>> >>> _*/ * ) >>> *Joe DeMers - owner * >>> >>> Sound Marine Diesel LLC >>> >>> SoundMarineDiesel.com <http://www.soundmarinediesel.com/> >>> >>> *phone & fax (860) 666-2184 <tel:%28860%29%20666-2184> * >>> >>> >>> >>> >>> On 2/24/2012 12:10 PM, Allen Edwards wrote: >>>> >>>> >>>> Thanks Joe, >>>> >>>> The L-36 has a designed LWL of 28 feet. I have not >>>> measured the actual. The engine HP is 31 @ 2200 RPM >>>> but I have been told to run it closer to 1200-1300 RPM. >>>> Design weight is 12000 pounds. The gearbox is 1:1. >>>> The boat specification is 14 inch prop and that is >>>> what is on there now so I want to stick with that size. >>>> It is also larger than the 13RH9 3 blade I took off the >>>> boat. I want a folding prop, likely a 2 blade >>>> non-geared Martec. >>>> >>>> Allen >>>> >>>> PS. I see lots of hits to your article on my web site. >>>> If you ever write another I would love to post it. >>>> >>>> >>>> On Fri, Feb 24, 2012 at 8:53 AM, Joe DeMers >>>> <je… [at] mindspring.com >>>> <mailto:je… [at] mindspring.com>> wrote: >>>> >>>> Start here - >>>> >>>> max diameter prop that will fit the boat. >>>> >>>> Load waterline of hull >>>> >>>> engine hp @ what? rpm >>>> >>>> reduction gear ratio. >>>> >>>> >>>> >>>> Send that info, and I will get you a prop >>>> recommendation. >>>> >>>> _*/ * ) >>>> >>>> *Joe DeMers - owner * >>>> >>>> Sound Marine Diesel LLC >>>> >>>> SoundMarineDiesel.com >>>> <http://www.soundmarinediesel.com/> >>>> >>>> *phone & fax (860) 666-2184 >>>> <tel:%28860%29%20666-2184> * >>>> >>>> >>>> >>>> On 2/24/2012 11:32 AM, Allen Edwards wrote: >>>>> >>>>> I am facing a decision on my prop. As part of >>>>> getting my Grey Marine 4-112 rebuilt I need to >>>>> also do something with the old Martec folding prop >>>>> as my diver says it needs servicing, which I have >>>>> never done. I need to decide repair or replace on >>>>> the prop. One of the questions I have is do I >>>>> have the best size prop. Without actually knowing >>>>> what size the existing prop is, this is really a >>>>> difficult question but I do have a fair amount of >>>>> information. Here is what I know: >>>>> >>>>> * Lapworth specified 14RH8 on the blueprint >>>>> for the L-36 >>>>> * The 3 blade that was on the boat when I got >>>>> it was a 13RH9 >>>>> * I removed the 3 blade and installed the >>>>> Martec folding that was in the lazarette. >>>>> * I dove to measure the prop and it measured >>>>> 14 inches with an angle at 2/3 or the way >>>>> out of 11-16 degrees which would mean a >>>>> pitch in the 6 to 8 range. Not that close a >>>>> measurement I know. >>>>> * The Grey Marine Engine manual suggests 14x9 >>>>> or 13x10 for that size engine (no mention of >>>>> boat size or power vs sail) >>>>> * Engine vs Boat Speed with existing prop: >>>>> * 1500 - 5.7kt >>>>> * 1250 - 4.9kt >>>>> * 1000 - 3.6kt >>>>> * 750 - 2.4kt >>>>> * The above measurements were taken with my >>>>> old worn out engine which has 40 psi >>>>> compression. It ran fine. >>>>> * I have a vague memory of seeing a graph my >>>>> dad did showing the boat was faster at any >>>>> given RPM with the fixed blade. >>>>> * Cruising RPM per my mechanic is around 1300 >>>>> * Maximum HP 31@2200RPM per engine manual >>>>> * Repair prop $210 + shipping ($30) + labor ? >>>>> ($70) = $310ish >>>>> * New Prop of newer design $710 + shipping + >>>>> labor? = $750ish >>>>> * I put 30 hrs a year on the engine, basically >>>>> only race or go to races. I just say this >>>>> to point out I need a low drag prop. >>>>> >>>>> Rebuilding is cheaper but if I am told the more >>>>> modern design backs up better, whatever that >>>>> means. There is no way I could back up worse as I >>>>> can't back up at all. All reverse is good for is >>>>> stopping the boat and does that well with no >>>>> problems. I blame the offset prop that sits above >>>>> the rudder so there is no backwash against the >>>>> rudder for the backing problems although I am told >>>>> that isn't correct, another story. >>>>> >>>>> The other question is, with the information above, >>>>> do I have the right prop on the boat now? If I >>>>> can get better performance with a new prop, this >>>>> would be the time to get it. There are basically >>>>> two ways that it might be worth getting a new prop >>>>> >>>>> * Better backing which I have to take either >>>>> on faith or from testimonial from one of you >>>>> * Better boat speed because the results above >>>>> indicate I have the wrong prop pitch >>>>> >>>>> Any thoughts? Joe??? Others??? >>>>> >>>>> Allen >>>>> >>>>> No virus found in this message. >>>>> Checked by AVG - www.avg.com <http://www.avg.com> >>>>> Version: 2012.0.1913 / Virus Database: 2114/4829 - >>>>> Release Date: 02/24/12 >>>>> >>>> >>>> -- >>>> >>>> *Joe DeMers - owner * >>>> >>>> Sound Marine Diesel LLC >>>> >>>> SoundMarineDiesel.com >>>> <http://www.soundmarinediesel.com/> >>>> >>>> *phone & fax (860) 666-2184 >>>> <tel:%28860%29%20666-2184> * >>>> >>>> >>>> >>>> >>>> No virus found in this message. >>>> Checked by AVG - www.avg.com <http://www.avg.com> >>>> Version: 2012.0.1913 / Virus Database: 2114/4829 - >>>> Release Date: 02/24/12 >>>> >>> >>> -- >>> >>> *Joe DeMers - owner * >>> >>> Sound Marine Diesel LLC >>> >>> SoundMarineDiesel.com <http://www.soundmarinediesel.com/> >>> >>> *phone & fax (860) 666-2184 <tel:%28860%29%20666-2184> * >>> >>> >>> No virus found in this message. >>> Checked by AVG - www.avg.com <http://www.avg.com> >>> Version: 2012.0.1913 / Virus Database: 2114/4829 - Release >>> Date: 02/24/12 >>> >> >> -- >> >> *Joe DeMers - owner * >> >> Sound Marine Diesel LLC >> >> SoundMarineDiesel.com <http://www.soundmarinediesel.com/> >> >> *phone & fax (860) 666-2184 <tel:%28860%29%20666-2184> * >> >> >> >> >> No virus found in this message. >> Checked by AVG - www.avg.com <http://www.avg.com> >> Version: 2012.0.1913 / Virus Database: 2114/4831 - Release Date: >> 02/25/12 > > -- > > *Joe DeMers - owner* > > Sound Marine Diesel LLC > > SoundMarineDiesel.com <http://www.soundmarinediesel.com/> > > *phone & fax (860) 666-2184 <tel:%28860%29%20666-2184>* > > > > > -- *Joe DeMers - owner* Sound Marine Diesel LLC SoundMarineDiesel.com <http://www.soundmarinediesel.com/> *phone & fax (860) 666-2184*