I can't figure out this math, please help.
08-24-2008 | 03:11 PM
#21
Registered
Joined: Aug 2004
Posts: 4,788
Likes: 1,377
From: naples,florida
It was a single in a direct drive inboard Parasail boat.Never had a pyrometer on it .
The heat damage was the exhaust manifold melting through by the Turbo on 2 occasions and the turbos housings cracking after every thousand hours.
Engine never ran hot on the gauge And was always left to idle and cool down after running on plane.
Only answer I ever got from Yanmar was the motor was a light duty motor and if I wanted reliability to step up to the 350 engine whick I think is now a 420
The heat damage was the exhaust manifold melting through by the Turbo on 2 occasions and the turbos housings cracking after every thousand hours.
Engine never ran hot on the gauge And was always left to idle and cool down after running on plane.
Only answer I ever got from Yanmar was the motor was a light duty motor and if I wanted reliability to step up to the 350 engine whick I think is now a 420
08-24-2008 | 03:11 PM
#22
Registered User
Joined: Feb 2008
Posts: 610
Likes: 1
From: West edge of the Pacific
Couple beers short of a 6 pack
Assuming the motors will pull the prop a 30 pitch at 3800 at 10% slip will put you at 64 mph,at 32 pitch at 15% slip will put you at 65 mph,you can play with the numbers on the prop calculator website,Smitty
http://www.rbbi.com/folders/prop/propcalc.htm
http://www.rbbi.com/folders/prop/propcalc.htm
08-24-2008 | 03:16 PM
#23
Registered
Joined: Aug 2004
Posts: 4,788
Likes: 1,377
From: naples,florida
I heard they where discontinuing the 315.
Buddy of mine that does all the warranty work on Hinkleys has had a field day working on the Yanmars lately.A lot of problems with the after market coolers and such on them creating major problems.
He told me Hinkley is swicthing to Volvos from now on.
Don't shoot me I am just the messenger.
Buddy of mine that does all the warranty work on Hinkleys has had a field day working on the Yanmars lately.A lot of problems with the after market coolers and such on them creating major problems.
He told me Hinkley is swicthing to Volvos from now on.
Don't shoot me I am just the messenger.
08-24-2008 | 03:23 PM
#24
Thread Starter
Registered
Joined: Jun 2004
Posts: 3,062
Likes: 0
It was a single in a direct drive inboard Parasail boat.Never had a pyrometer on it .
The heat damage was the exhaust manifold melting through by the Turbo on 2 occasions and the turbos housings cracking after every thousand hours.
Engine never ran hot on the gauge And was always left to idle and cool down after running on plane.
Only answer I ever got from Yanmar was the motor was a light duty motor and if I wanted reliability to step up to the 350 engine whick I think is now a 420
The heat damage was the exhaust manifold melting through by the Turbo on 2 occasions and the turbos housings cracking after every thousand hours.
Engine never ran hot on the gauge And was always left to idle and cool down after running on plane.
Only answer I ever got from Yanmar was the motor was a light duty motor and if I wanted reliability to step up to the 350 engine whick I think is now a 420
Did you have one of the earlier 315's?
08-24-2008 | 03:35 PM
#25
Charter Member # 55
Joined: Oct 2000
Posts: 20,271
Likes: 2,512
From: Omaha/LOTO
Right @ 60-mph would be my guess. I have already put in an email to to Max Machine Worx guys, I've never met them but their work is well spoken of in our area. I will have them do a 1.36 swap and if they have any goodies they can add while they are in there we will do that too. None of this happens til Feb anyhow so there is time to get a solid plan together.
Probably something in the 26" range then at 3800 will put you into the low 60's.
08-24-2008 | 03:39 PM
#26
Charter Member # 55
Joined: Oct 2000
Posts: 20,271
Likes: 2,512
From: Omaha/LOTO
08-24-2008 | 05:20 PM
#28
Charter Member # 55
Joined: Oct 2000
Posts: 20,271
Likes: 2,512
From: Omaha/LOTO
At 3800rpms, in my 32 Active Thunder with 1.36 drives and 24 pitch props, I'm right around 55mph.
My propslip remains pretty constant at about 13-14% from 3800rpms through WOT.
My propslip remains pretty constant at about 13-14% from 3800rpms through WOT.
Last edited by Griff; 08-24-2008 at 05:23 PM.
08-24-2008 | 05:45 PM
#29
Banned
Joined: Oct 2006
Posts: 5,844
Likes: 0
From: Bradenton Florida
3800 X 24 / 1.36 X 0.01 / 12 = 55,882 MPH
And if you do it that way you get the most acc. speed and slip calculation.
RPM X PITCH / RATIO X 0.01 / 12 = SPEED with 00.00slip !
08-24-2008 | 06:57 PM
#30
Registered
Joined: Jun 2004
Posts: 1,395
Likes: 20
From: Freehold, NJ
Griff,
That's what I was looking for. Metal's original question is based on a 1.5 reduction gear not the taller 1.36's you have. You validate my point that it's prop speed and not pitch for going faster, of course pitch plays into it but you need sheer rpm's to go fast!
Also how much Hp are those engines and at what max rpm? I'm driving at proving my point here a little more so help me out please?
Joe Gere
That's what I was looking for. Metal's original question is based on a 1.5 reduction gear not the taller 1.36's you have. You validate my point that it's prop speed and not pitch for going faster, of course pitch plays into it but you need sheer rpm's to go fast!
Also how much Hp are those engines and at what max rpm? I'm driving at proving my point here a little more so help me out please?
Joe Gere
Last edited by HabanaJoe; 08-24-2008 at 07:10 PM.
