What would be the best engine and drive

[Xtreme]

For a 40 ft aluminium, 2.600 KGS, monohull cigarrette like hull boat,

What would you suggest the best engine/s and drive/s type to move this boat, to be able to do 60-70 MPH at sea and carry 12-16 passengers on exciting rides.

Many thanks

[rasorinc]

A pair of GM marine inboard engines LSA 6.2L V8 SC. HP is 530 each. See details
on this GM marine engines site. They are lightweight aluminum blocks. I would go with standard inboard setups. However, surface drives give you a little more speed but standard inboards give you better reverse and control.
http://www.gm.com/experience/technology/gmpowertrain/engines/specialized/marine/marine_engines.jsp

[Xtreme]

Thanks. I will look into it.
Would 2 petrol Mercruisers x 365hp and jet drives be sufficient and give a fast speed or not?

[masalai]

In 10 years you may want one that does not need petro-chemical fuels :D:D:D

[fasteddy106]

In 10 years you may want one that does not need petro-chemical fuels :D:D:D

Cultist!:D

[masalai]

You really need to join my cult, - - for survival in the future:D:D:D:D

[Xtreme]

I am only interested in powerboats. Sorry but I still have better things to do than hiding away from the family by sailing and drinking cases of beer.
Thanks but no thanks!

[mongo75]

How about twin deisels mated to heavy duty Merc drives? You'd get more torque and fuel economy than a gas engine. Plus if your lucky you can find biodiesel cheaper than #2

[marshmat]

All true, Danny, but at what cost?

Mercury-marinized GM engines tend to sell for about $50 to $100 per horsepower. High-revving performance marine diesels often cost double that- and $300/hp is not at all uncommon. And, pushed to the limit like this, either option is going to be very demanding on its mechanic, probably needing rebuilding after a couple thousand hours.

For a cigarette boat- essentially a big toy- that might only see 60 to 100 hours of use in a year, the hundred-thousand-dollar difference might well buy more fuel that the boat will use in its lifetime.

The question must be asked, though- what's with the 16 passengers? If you're just out to give tourists a thrill ride, there's no need to go over 45 mph. Get landlubbers out there at 40, they'll think they're doing 80 as long as you don't get passed by a boat that really is doing 80. Drop the trim and the tabs at 30 mph, put the helm hard over, and bring up a huge wall of spray- that's what the "speedboat experience" is about, for the passengers.

[apex1]

The question must be asked, though- what's with the 16 passengers? If you're just out to give tourists a thrill ride, there's no need to go over 45 mph. Get landlubbers out there at 40, they'll think they're doing 80 as long as you don't get passed by a boat that really is doing 80. Drop the trim and the tabs at 30 mph, put the helm hard over, and bring up a huge wall of spray- that's what the "speedboat experience" is about, for the passengers.

Right Matt, and on top: I doubt you get a 40ft carrying 16 pax to 80kn with some shabby 1000 horses. Double that, at least (and pay the price). The 10cyl. MAN are the engines of choice in that case, coupled with Arnesons. Just 500.000$ over the counter.

Regards
Richard

[marshmat]

Of course, Richard, if one really wants a boat to go fast on a tight capital-costs budget, one could go to an aircraft wrecking yard and hunt down a worn-out heavy lift helicopter... the 11,240 hp Lotarev D-136 engine used in the Mi-26 comes to mind....

[apex1]

Of course, Richard, if one really wants a boat to go fast on a tight capital-costs budget, one could go to an aircraft wrecking yard and hunt down a worn-out heavy lift helicopter... the 11,240 hp Lotarev D-136 engine used in the Mi-26 comes to mind....

Perfect solution! ten points Matt;) The passengers you can have in tow then.

[mongo75]

$300 per hp?? What crazy ass is quoting you this?? I re-built a Chevy 350 for under $750 US, and it pushed my 25' 5000lb Bayliner at 32mph. I would guess it was good for 300hp. I can't afford the rediculous prices that many retailers feel thier parts are worth, so I find used stuff, and rebuild it myself with reliability and cost in mind. SO my Chevy cost me about $2.50 per hp, a helluva lot less than $100 per hp!!

[mongo75]

And another thing- unless that $100 per hp you quoted me includes a drive, there's not stinking way it can be that much- I mean hell you can buy a nice GM crate motor for under $6000 RTR, and just bolt on the misc. Marine parts, and you still come in under $9000. So with a little elbow grease, you can save a LOT of money. "MARINIZED" is just a fancy word to get you to throw money away....

[apex1]

Mongo
there are no marinized MAN engines around, these are Marine Engines by design. And Diesels.
They do´nt compete with these old GM gas guzzlers designed in the 30ies of the last century.
Getting a 25´ on 32kn does´nt mean anything if you´re planning to get a 40´ on 70kn, right?
So compare apples and apples to get called serious.
And, yes the price mentioned included the Arnesons and gear. We pay these prices several times every month (not the Arnesons) and our customers do´nt argue.

Regards
Richard

[mydauphin]

In 10 years you may want one that does not need petro-chemical fuels :D:D:D

If you believe this then buy your sailboat now. There will always be petrofuel and people willing to use it.

[masalai]

That, I am doing, - - But will you be able to afford it in 10 to 15 years time?

[marshmat]

A Merc HP525EFI, 8.2 litre V8 putting out 525 horsepower, regularly shows up on the Web for $34,000 USD. $65/hp, you *might* get a Bravo 1 drive included in that price if you're lucky, and this is fairly simple as speedboat engines go. A supercharged, 9.1 litre 1075 hp Merc that would be more suited to the stated intentions of the original poster in this thread runs $100k plus drive, there's $93/hp for the engine alone. The $50/hp ballpark will get you a new Merc or Volvo marinized 3.0, 4.3 or 5.0 litre motor, of a design dating to pre-1980 (albeit with modern EFI), and a basic outdrive or gearbox.

None of the marine diesel manufacturers are particularly forthright about their pricing structures- you pretty much have to find a dealer and get an application-specific quote. But $100k for a high-performance, high-speed 500 hp diesel appears to be relatively common. In the smaller sizes, the cost per horsepower can increase dramatically, sometimes as much as $300/hp, if you want a light, high-power diesel with the best of the best in modern computer controls and exotic alloys.

Being able to build your own engines will certainly reduce the cost, Danny. Your own experience is wonderful proof of that. Still, the price difference between a home-rebuilt Chevy 350 and a brand-new, professionally installed 10-cylinder MAN is shockingly huge.

[mongo75]

Oh I know there is definitely a difference between a 350 and a nice MAN LOL. My issue is that I can't afford that, so I do what I can to make ends meet. You could find Cat diesels, or Deeres, and marinize them, but like you said, there is a difference in pushing a 25' boat and a 40' boat. I guess I shoulda said that "I" would exhaust all means searching for a less expensive route that would achieve your goals before I settled on paying for a brand new drive set up. But if ya got the money, then hell, go for it! I would!

[marshmat]

I guess I shoulda said that "I" would exhaust all means searching for a less expensive route that would achieve your goals before I settled on paying for a brand new drive set up
So would I, my friend. So would I.
I have very little interest in owning an engine that costs as much as a house!

[Frosty]

You are doing this the wrong way round. Tell your prop man what you expect from what boat and what weight and speed. He will then give you a choice of props and gearbox ratios and engines with required HP and RPM.

Don't just slap in some motors and some second hand gearboxes then expect the prop man to get you out of the ****.