Outboards for RIBs

[MarcusMan]

We're thinking of getting a RIB (I know Raving Idiots Boat!!!!) and I was wonbdering if the forum has any comments on the advantages / disadvantages of 4-stroke v modern 2-stroke. The boat we're currently eyeing up has a 200HP Yamaha HPDI engine thats claimed to be much more fuel efficient than a "normal" 2-stroke and providing much more torque than a 4-stroke

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[Dave_Snelson]

The Yam 200 is a cracker (providing its been treated well) and if the hull is as good as the motor, then buy it. The HPDI gives the advantages of 4 stroke in a 2 stroke package.

4 strokes are heavier, as a general rule, and more expensive on initial outlay, again as a general rule. The advantages are quitness, fuel economy and lower pollution. Only time will tell when it comes to overall reliability.

By the way, if I was starting out again, I would buy a RIB. They don't sink, they can take rough seas, they are good safety boats / dive boats / ski boats / anything boats. When the weather turns unexpectedly rough and you have your family to get home, you'll be glad you bought a RIB! Why are most life-boats RIB's?? I rest my case your honour....

All IMHO, of course.

<hr width=100% size=1>Madoc Yacht Club
<A target="_blank" HREF=http://www.madocyachtclub.co.uk>http://www.madocyachtclub.co.uk</A>

 

[andyball]

"more torque" tends to be trotted out for two or four stokes, depending on the ad' agency's whim .

What some four strokes do have ( at least the larger ones) is a bit of a flat spot round 4000rpm....if that corresponds with just getting on the plane, they can seem rather lifeless compared to a 2-stroke of the same power rating.Unless it's a big rib, you'd be well planing by 4000rpm with 200hp on the back.

hpdi's are much more economical than a normal 2-stroke,but prob. not as good as a 4-stroke, esp. at v.low speeds.

Many people say 4-stokes too heavy, but often the extra fuel a 2-stroke boat must carry for the same range evens things out (less so with hpdi engines,I s'pose.)

for what most people use ribs for, a 200hp hpdi is excellent,but so's a modern 4-stroke 225.

in practice, you'll notice that the 2-stroke cowling is prob. much heavier, but no big deal....& no doubt the 2-stroke piston/ring life will be shorter, but probably well past the first few owners unless used v.long/hard.

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[AJW]

Ravin Idiots Boat, thats a new one /forums/images/icons/smile.gif

I run a 200 Yam HPDI on a 7.5m RIB and its a cracking piece of kit. Akershally they both are as the boats a Scorpion. Anyway, 4 strokes in the main are nasty heavy things more suited for cars. 2 strokes are nice light weight hi-revin things that give you plenty of poke.

My Yam gives me 45kts+ flat out but at 30-35kts burns roughly 1l per mile. Which is good going IMHO. I had an old 150 carb 2 stroke some years ago that did about twice that on a good day. Yams have a reputation for being better engineered than Merc / OMC. Its certainly quieter than a Merc/Mariner Optimax. I would steer clear of any OMC Ficht outboard before 2002 when Bombardier got them sorted. Also whatever the deal you are offered steer clear of conventional/old tech 2 strokes unless you have shares in an oil refinery. Oh yes, another thing HPDI's run on ordinary TCW3 2 stroke oil whereas Optis & Fichts need fancy own brand and more expensive oil.

What sort of RIB are you looking at?

Finally for a forum fix on all things RIB you should make your way to rib.net where everyone apart from the occasional glastron owner is welcome.

AJ

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[MarcusMan]

AJ

Its a Ribeye 750 Sports. New last year, with a custom built cover and various other bits and pieces. Compared with the new list price it seems a good deal.

Mark

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[Will_M]

I run a RIBTEC585 with Yam F100, much smaller than what your looking at, but the point being I just thought I'd wave the flag of support for all things Yam.

Having used a selection of outboard brands both 2-stroke and now 4-stroke I would never now look anywhere else other than the Yam outboards.

Well supported products, cant go to far wrong.

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[AJW]

Ooohh, Ribeyes now built in South Africa with PVC tubes and dodgy build quality. At least thats the word I've heard. I'd stick to mainstream Hypalon and decent built boat. If you intend to do any serious Ribby stuff for gods sake get jockey seats or a leaning post so you can stand up. A bench seat in any kind of sea and at any speed is a dreadful thing!

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