How many HP?

[Tom]

I need some advice as I've only pottered about on flat water in a RIB.

I know it's a length of string question but bearing in mind I wouldn't be setting out unless the water was pretty calm how many HP would you need to be safe at sea pottering around the coast if it got a little choppy in say a little 10ft F-RIB with 2 people on board?

Thanks in advance for any advice.

[mattswan2512]

Id say 10hp mate or a 8 - 9.8 2 stroke minimum. You would be fine 1 up with 5 hp in calm seas but 2 up it will die and will not probably plane....
Get as much hp as you can afford and carry is my advice as it makes your boat versatile for different trips. You can go slow with big power but should you need more speed its not available from smaller hp engine for eg a mate had a 5 hp on a 3.5m honwave. It flew (for a 5hp) in mild currents at about 12knotts but up against an outgoing spring heading bk up the hamble 1 up it barely made headway so most power you can afford or transport..... simple equation.

Have fun sibbing!!!

[neil h]

Check out Gurnards Frib (Guppy) thread. He had 11mph and was planing in a small frib 1 up with a 3.3.

I agree with Matt though... for coastal I would want 8hp min I think.
A friend came with us last year in a 3ish metre avon rib, with an 8hp, which got at least 17mph, it may have been knots but I forget. That had 1 adult and one child on board. So 8 would be a good starting point.

[Martin]

The f-rib will go much faster and get on the plane much easier than any sib out there. The horsepower required is much less than a standard flip flop sib requires.
You could read & infact should read the gurnards post "the guppy" to understand how the FRIB performs with a squirty engine, but then take into account the gurnards wealth of experience and understanding of the conditions surrounding him, both how it is and what he's see's coming.

I personally, and this is just prob me..
Wouldn't venture out to sea with anything less than 8/9/10hp.
I have had my 3.8 Honwave on Langston, 2 up, fuel etc and my 1978 2 smoke 9hp Suzuki shoving us along approx 18-20mph.
However, that is an outstanding low hrs engine with a steel prop.

Hope that helps

Martin

[neil h]

By the way, I now have a Mercury 10XR to sell if of any interest... 2001 if I remember right, and really clean under the hood.

[stigoftd]

Out in open water you need the ability to plane and out run any breaking sea - i have my 2.8mtr air deck sib rigged with a 15hp and mainly its just me on board but i know i can get through and out run any seas ime likely to encounter

but also it is just as well at home plodding about creeks and esturies

the only down side i can think of is weight but for me as ime usualy on my own i have a tiller extention and sit further forward

if i was using a 3mtr ide have a 20hp min but thats becuse i dont mind what the weather is doing and enjoy the rough just as much as the calm so power is a definate for me

[Paul B]

I've got a 3.2 Honwave with a 15 on the back , this is ideal . Certainly quick enough to get you out of trouble ( or into trouble ). But I wouldn't want to have any less power than a 8-9 hp on the back,

[Tom]

Thanks for all the advice. I would have prefered the weight and size of a 5HP but I suspected I needed at least 10hp at sea.

[Si Crowe]

if weight is an issue (which it will be on a small boat) look at 2 strokes. a 9.9 hp will be the same size and weight as a 15hp (Mariner & yamahas are identical as are evinrude and johnson) as for the most part manufacturers tend to just use a smaller carb on the 9.9. a 4 stroke is alot larger and heavier for the same power. if the sib/rib is rated to 15hp, id just get the 15hp 2 stroke as you can store it any which way you want and will be a lot more compact and easy to heft about.

plus two up, you still be able to plane no worries and have the power to deal with tides and seas.

[9-R]

Out in open water you need the ability to plane and out run any breaking sea.

I agree!

I wouldn't have thought this to be such an import factor until we were caught of guard on one of our initial voyages along the coast. What started out as calm waters has quickly turned on us before. We have a 20hp but with a larger boat and a lot more weight. We get around fine but at that moment, I really had wished we had more power!

Like has been said, I think you should get the biggest you can find, afford or handle if you're heading out onto the ocean in case it's needed.