43' with outboards?

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Noahsmom

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Jun 14, 2004
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Our 43' Silverton currently has twin diesels, my husband is considering putting twin 225hp outboards on an extension platform. The boat will weigh approx. 15,000 without the diesels and without fuel, water, & people. Can this be done? If so, how will it handle? Are twin 225's enough power?
 
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Noahsmom

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Jun 14, 2004
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Re: 43' with outboards?

He told me 2 motors would consume the same fuel as the diesels (1mpg). So wouldn't 3 be 1.5gpm? I'm just not convince that going outboard is the thing to do. If he needs to replace the diesels then I think we should go back to gas inboard which was orginally in the boat from manufacturer.
 
JB

JB

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Re: 43' with outboards?

Hi, Mom.<br /><br />I really doubt that twin 225 outboards, even 4 strokes, would deliver even close to the fuel efficiency of a pair of Diesels of near that hp.<br /><br />They would give you a LOT more cockpit space and probably weigh a lot less, but I would expect them to use a lot more fuel.<br /><br />Just one opinion, not knowing what Diesels you have.<br /><br />Good luck. :)
 
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Dhadley

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Feb 4, 2001
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Re: 43' with outboards?

Just as a reference, we did a 32 Excalibur some years back. We replaced 2 454 Mercruisers with 3 275 hp V8 Johnsons. <br /><br />With the Mercruisers the boat ran about 53. With the outboards it just touched 70. With the outboards he could cruise at 35 mph at slightly over 3500 rpm. Using the same gas tank (whatever it would hold -- I dont remember) his range at crusing increased by over 33%. <br /><br />With todays direct injected outboards Im sure it would be even beter.<br /><br />You would need to look at the hull design closely as we went from I/O's to outboards. You are (most likely) going from an inboards. If the inboard and I/O hull are the same on your model boat it should work.
 
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Chris1956

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Mar 25, 2004
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Re: 43' with outboards?

Dhadley, That was an interesting conversion project. I never thought the fuel mileage would increase after the conversion! You added about 165 HP, and I will guess the weight stayed nearly the same. This explains the increase in perfromance. However, I had thought the inefficiency of the outboards would negatively affect the fuel useage. Also, your RPM at WOT would have been 7000+. Is that correct?
 
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Solittle

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Apr 28, 2002
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7,518
Re: 43' with outboards?

Lets look at fuel burn first. The rule of thumb is 1 gallon of fuel per 10 hp per hour at WOT. In your case that is 22.5 gal/hr/motor or 45 gal per hr for the twins.<br /><br />I would guess that two 225s would give you OK or marginal performance by the time you added fuel (& a lot of it)& stuff. You need to get input from others as I have little experience with this sort of thing.<br /><br />I would do a lot of research before attempting this. There have been several posts here from folks who have done this and all I remember is that they had problems with handling, balence and performance.
 
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