[TedM]

Maybe this has been answered before, but I did a search and came up empty. When a boat has twin outboards, say 150's or 200's, what is the true horsepower value? Just because someone has 2- 150 or 200's on the transom, it doesn't really give them 300hp or 400hp does it?

Thanks for the patience on a possible dumb question for some...

[TidesHHI]

quote:Originally posted by Ted M.:
Maybe this has been answered before, but I did a search and came up empty. When a boat has twin outboards, say 150's or 200's, what is the true horsepower value? Just because someone has 2- 150 or 200's on the transom, it doesn't really give them 300hp or 400hp does it?

Thanks for the patience on a possible dumb question for some...

I've often wondered the same thing.

Many boats are rated for 300-500 HP. This is not possible with a single outboard. Using this logic, then yes, you have twice the power. However, you do not necessarily have twice the speed.

[CaseyP]

Yes, if you have 2 200 HP motors, you have 400 HP. You don't have the equilivant of one 400 HP motor in speed though. Reason being that you have more drag caused by the second gearcase.
I can only assume that there would be Prop issues and gearing issues between a single set up and twins. There is also a weight factor to take into account.

[AC]

What Casey said.There is a loss factor,but I can't remember what it is.I think it was around 15%

[Chessie]

There is not always necessarily a loss factor. It is true that you have extra drag from the second gear case, but you also have an extra prop pushing water.

I have read a few test cases where identical boats were run with both single and twin set ups, usually with the sum of the horsepower from the twins being slightly less than the horsepower from the large single. In some cases, the boat with the twins showed better overall performance as far as speed, hole shot, and fuel numbers.

-c

-c

[modunlavy]

If comparing same total hp of 2 engines vs one, you should get better numbers out of the single. The single prop is more efficient than the two, the one motor has less drag etc.

As odd as it sounds though, you can sometimes get better cruise performance with twins with more hp than the single (say like twin 150 vs a single 225). This is because you can run the twins at a lower cruise RPM which can be more efficient fuel burn wise for the twins than the single.

But, when you figure in overall maintenance $$$, it gets really hard to say it is 'cheaper' to run twins!!!

If you need or want 400 hp though you don't have too much of a choice unless you want to go with diesel inboard or i/o.

md

[fishin-fanatic]

To get a very clear idea of how the exact same boat will perform with a variety of single and twin engine set ups, go to this link on the Regulator web site. They have tested the 23-footer with the following engines:

single 250 EFI
Single 225 4-stroke
Twin 115 4-stroke
Twin 150 HPDI's
Twin 200 HPDI's

[Kat-Man-Do]

uh.... what link?????

[Tuna Man]

Another thing to add is the additional weight of the twins, twin props, twin full oil tanks, etc. Also I have to assume that some boats ride a little stern heavy when fitted with twins.

Scott S

[Mumblerone]

Regulator boats at www.regulatormarine.com...to compare twin vs single. [img]/infopop/emoticons/icon_wink.gif[/img]

[fishin-fanatic]

Here's the link ..........

http://www.regulatormarine.com/frames_models_bl.html

Press the button for the 23 once you get there.

[BigBone]

I still say 350HPDI with clip on kicker for safety.

1998 Contender 25
225 Yami's