[Public-List] Engine Power Loss

Thu Sep 13 06:38:37 PDT 2007

Hi Brian - 

I tried out Surprise last night after our club's Wednesday night race.... We
do 6.7kts at 1,600 rpm; And when secured to the jetty the revs are still
1,600 rpm when the transmission is in forward and the throttle is full open.
(when asked by a neighbour what I was doing, I said that I was conducting an
experiment involving testing the amount of slack in the dock mooring
chains...)

I'd like to see your pictures too.

Do you live in Vancouver?

Gord #426 Surprise

> Just a general thank you to all on the list for the suggestions for fixing
> my power loss issue. I'm going to explore the gas filter suggestion as well
> as the switched high-tension leads. I read that in the past but doubt that I
> would get the RPM's as high with switched leads.
> Normally, on calm water, the engine pushes to hull speed at approximately
> 1200 RPM. But that's it. There is no reserve if pushing against a current.
> I have a few pictures of the restoration work I have done to Putachieside as
> well as a couple of great pictures (at least I think their great) of my wife
> and I sailing in Boundary Bay BC on September 9. If you wish to see let me
> know or George, if you can post some, tell me where to send them.
> 
> Cheers - Brian - #496
> 
> 
> -----Original Message-----
> From: public-list-bounces at lists.alberg30.org
> [mailto:public-list-bounces at lists.alberg30.org]On Behalf Of Meinhold,
> Michael J.
> Sent: Wednesday, September 12, 2007 8:35 AM
> To: Alberg 30 Public List -- open to all
> Subject: Re: [Public-List] Engine Power Loss
> 
> Gord - I think this is a good way to look at it.  Most ships have prop
> and engine tuned for max efficiency at somewhere below the "hull speed".
> Tugboats are and interesting exception because they have to be efficient
> at very low to zero speed - they are generally qualified by a "bollard
> pull" test against a dynamometer at the pier.
> 
> My tach has been busted all season, but from memory I agree, I get 6.5
> knots at much less than 2000 RPM.
> 
> 
> Mike
> Rinn Duin #272
> 
> 
> -----Original Message-----
> From: public-list-bounces at lists.alberg30.org
> [mailto:public-list-bounces at lists.alberg30.org] On Behalf Of Gordon Laco
> Sent: Wednesday, September 12, 2007 11:20 AM
> To: Alberg 30 Public List -- open to all
> Subject: Re: [Public-List] Engine Power Loss
> 
> I agree - I was thinking the same thing.  FYI SURPRISE gets about 6.5 at
> about 1400 rpm; I have never tried revving up to full power at the
> jetty.
> If you have a slightly heavier pitch on your prop your revs will show a
> little lower at full throttle as the boat comes up against the
> steepening resistance curve due to that old 1.4 x the square root of
> your effective waterline length.  At rest, and with the water flow past
> the prop not being what it might be while moving fast, the 'slippage'
> will be greater possibly allowing the revs to go up as the efficiency of
> the prop drops a little.
> 
> Mike - am I on track with that reasoning?
> 
> Gord #426
> 
> 
>> You may get 2000 RPM at the dock straining against the docklines, but
>> since the prop is more efficient when the boat is moving forward, it
>> absorbs the maximum power of the engine at lower RPM.
>> 
>> 
>> What's your speed at 1200 RPM underway?
>> 
>> 
>> Mike Meinhold / Naval Architect / SAIC
>> 4321 Collington Road, Suite 250, Bowie, MD 20716
>> Office: (301) 352-4734  Cell : 410 271 5394
>> Michael.j.meinhold at saic.com
>> 
>> 
>> -----Original Message-----
>> From: public-list-bounces at lists.alberg30.org
>> [mailto:public-list-bounces at lists.alberg30.org] On Behalf Of Cole,
>> Andrew L
>> Sent: Wednesday, September 12, 2007 7:48 AM
>> To: public-list at lists.alberg30.org
>> Subject: Re: [Public-List] Engine Power Loss
>> 
>> Brian,
>> 
>> It is puzzling that you can get power in gear at the dock, but not
>> underway.
>> 
>> This may be directly or indirectly a fuel quality issue.
>> 
>> If you have a fuel filter, yank the element and see if it's all full
>> of crud.  The ethanol gas in particular does not get along well with
>> water and will go bad quickly.  That can gum up your carb., or worse,
>> stick a valve.  If the filter is crud-filled, drain the tank, get a
>> better sealed filler cap, change the filter element and re-fill the
> tank.
>> 
>> If you have access to a compression tester, check each of the
>> cylinders to ensure you don't have a stuck valve.  These low
> compression 4cyl.
>> engines will run well enough on two cylinders to fool a mechanic into
>> thinking it's running normally unless he puts load on it.  If you
>> don't have a compression tester, you may be able to see the valves
>> through the spark plug holes, if so, you can check to see that each is
> 
>> moving up and down on each pair of revolutions.
>> 
>> If you're lucky, neither is the case, but you may as well check to
>> eliminate possible causes.
>> 
>> Andrew Cole
>> Andante - 152
>> 
>>> When the transmission is in forward, neutral and reverse at the dock
>>> I
>> get about 2000 RPM.
>>> However when I leave the dock I cannot get the RPM's over 1200 in
>> forward.
>> 
>>> Brian - Putachieside - 496
>> 
>> Cole, Andrew L
>> Admitted in Maryland, Virginia & Florida One Corporate Center
>> 10451 Mill Run Circle, Suite 1000
>> Baltimore MD 21117
>> 
>> 
>> tel: 410 581-7408
>> fax: (410) 581-7410
>> mob: (410) 206-3577
>> 
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