T&T: HP ratingse versus hul speed

[Bill Allen]

It all boils down to trying to make a boat do everything which is mostly not 
possible. All that said my old 43 hatt aft cabin will do almost 2 mpg at 
hull speed. Non turbo so it's not a problem. That said push it up to 13 and 
now we're talking .6 (thats point six) what a difference. As far as being 
able to move a boat in current you also need wheels with a bite, again more 
hp.. Of course the current trend to mini mega yachts with sloping decks and 
very high cabins makes the whole manuering thing a non issue, you can't make 
them move in almost any wind. Bill
----- Original Message ----- 
From: "Arild Jensen" <elnav@telus.net>
To: <trawlers-and-trawlering@lists.samurai.com>
Sent: Monday, November 13, 2006 1:18 PM
Subject: Re: T&T: HP ratingse versus hul speed


>> -----Original Message-----
>> From: Bill Allen
>> I was on a 49 defever with a pair of 375 3208's at over 3 times
>> the standard hp for this boat it didn't even double the speed, what's the
> point? Bill
>
>
> REPLY
> EXACTLY!!
> I think this is a question of marketing running amok. Especailly in North
> America the notion that bigger is always better seems to predominate.
> However over-sizing the engine also means the engine is never run at its
> optimum loading when going at hull speed. Yes you can run at slightly 
> faster
> speed and get the engine into the sweet spot on the curve buit look at the
> fuel burn!!  ouch!!!
>
> If you have bothered to read any of the "Peak Oil" articles, you know that
> fuel prices will trend upwards.
> We are nto far way from $4 or $5/gallon and even higher priced diesel 
> fuel.
>
> These over powered trawlers and especially express trawlers (oxymoron?) 
> will
> become quite difficult to sell due to their fuel thirst. Dropping the 
> engine
> RPM down the curve to a point where only hull speed is acheived may also
> lower the loading enough that the engine is running cool. That is also 
> going
> to lower fuel economy from optimum.
>
> Personally I  do not see any point in using an engien larger than about 
> 15%
> more than called for at hul speed.
> Can anyone supply data to justify a larger percentage engine size 
> selection?
>
> regards
> Arild
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