What size outboard?

[muckypup]

Harlequin has a Valiant 3m RIB with a 4hp 2 stroke outboard. I think that this is a little underpowered as even with the throttle wide open and the engine screaming she doesn't move that fast... I would like a little more relaxed engine (and not sound like a 16 year old with his first moped) with some power in reserve for open water use.

I'm guessing that more HP = Heavier outboard, and 4 stroke = heavier than 2 stoke for the same given HP...

I was thinking about lookling for a second hand 2 stoke unit at about 10-15 HP... Is going to be enough for the above? Too much? or if I'm to change the outboard, should I be looking for even more HP? Or would the extra weight of the engine be too much?

Steve

 

[duncan]

Steve,

Searh around and you will find many ecent posts asking the same thing.

Possibly a gross simplification of the answers but the Tohatsu 9.8 2stroke is the 'forum choice'because it's the lightest in that class by a country mile and should give you around 20knots on your Valiant....................

 

[[2574]]

Steve,

I've been around this circle and to be honest I ended up exhanging our heavy rib (Avon 2.8m) for an airfloor Avon 2.8 with a 3.3hp Mercury. I much prefer the result - the whole setup is MUCH lighter and less demanding to use. With the old setup I'd found myself not nipping ashore for a pint because the whole thing was aggro - now I found it's easy to pop ashore. So, unless you want to plane at 20kts in the dinghy why not down size the whole rig rather than up size the engine?

rob

 

[Tisme]

There should be a plate on the RIB which will give the maximum size engine; I would guess it will be 20HP.

We have a slightly larger dinghy and used to have a 15HP engine on it. This would get the boat up on the plane with no problem with 2 people on board. It would struggle, but just manage, to get on the plane when 3 up.

Two up it would get up to 18knots. One up it would do well over 20kts, but I never measured it.

If you want to get on the plane I would go for 15 hp. If you are not interested in that then, personally I would go for 4-6HP to give a compromise between weight and reasonable speed.

With one person on board my dinghy can get on the plane (just!) with the current 3.3 engine, so a 6HP would probably manage without too much effort.

 

[Guest]

I agree ....

Probably with changing the outfit - you can actually buy second-user and get cash back ? Ribs are great ... but have drawbacks .... is it really necessary, could you swap the RIB for another style of Flubber and keep present engine ? and get the performance you want ?

Ity all depends on what you do and where ... if in harbour - then Ribs are an overkill I believe ... but if you regularly run in from anchorages - then a Rib is good compromise ....

Being a 3m RIB - I would guess that useage is in normally in reasonable closed waters ... so is it ideal ?

 

[muckypup]

Re: I agree ....

I thought about changing the rib, but I would like one that can carry 4 peeps (or 3 fat ones), SWMBO insists that it must be a rigid floor and not floppy. I havn't seen anything that matches that for less than a grand.... and I think that motor might still be a little underpowered...

Steve

 

[Guest]

Re: I agree ....

Agreed ..... difficult one ......

up to 10HP ???? 2 stroke .... sod the Greenpeace 4 stroke people .... in fact good 2T engines on market from those who have "upgraded" .......... using word loosely !!

 

[npf1]

Re: I agree ....

someone posted on here a few weeks agi that the late models of Honda 5hp four strokes can be derestricted very easily to 8hp. Don't know if it's fact or fiction but a 27kg engine giving 8hp sounds appealing.

 

[ralf2]

tohatsu 9.8 and your set up perfect!!