Originally Posted by Aegean Lady
What type / size of engine would be appropriate? I imagine we'd want two engines for safety reasons but I see you can get diesel or petrol. What are the advantages/disadvantages of each as far as ribs are concerned? (I'm sure this is very basic, but I want to appear knowledgable when speaking to our Principal) Diesels are easier to maintain I think, aren't they? And the fuel is less flammable?
I'm relatively new to it as well but have done a fair amount of research on here and elsewhere (if you do a search on RIBnet there is tonnes and tonnes of information and discussions from people much more knowledgeable than I will ever be). From my research I suppose you could say the basic plus/minus points seem to be:
Diesel: expensive to buy but cheap to run and as you say less volatile fuel. Probably more reliable? Almost always inboard I think so will take up space in the boat, if that is important to you? Also (not 100% sure about this) I guess they are likely to be a fair bit heavier.
Petrol: cheap to buy but expensive to run (esp older 2 strokes as I am finding out!) so range could be an issue if you are going long distances and cost could be an issue if you use it every day. Almost always outboard; I guess you can get petrol inboards but they seem rare so I suppose most people think like me - I'm twitchy enough with a petrol tank between my legs never mind sitting on the bit that makes it explode too
Petrol 2 stroke vs 4 stroke: 2 stroke cheaper and lighter but older ones are MUCH more thirsty than the new ones; 4 stroke expensive and heavier so you won't get the same HP engine before you get to the limit of what the transom can carry. Is performance critical for what you want? probably not.
Single engine: less cost to buy but when the fan stops then so do you, you can use a small auxiliary engine e.g. 4-6hp as many do, this is what I am doing, but the "get you home speed" is likely to be a bit dull, probably only 5 kts or so!
Twin engine: much more expensive to buy and maintain and it seems that you lose out in terms of performance i.e. two 75hp motors will probably not go as fast as one 150hp. However if properly set up with twin fuel systems/electrics (so that fuel contamination doesn't kill both engines) you have much less chance of breakdown as you still have half the power to get home on instead of bumbling home on 4hp.
If I was buying a new rib and could afford it I would probably have twin 4 stroke petrol outboards... or maybe a diesel inboard. As I can't afford a new RIB I have ended up with a single 2 stroke thirsty petrol outboard, and a 6hp four stroke aux. To be honest this probably provides just as much fun for a lot less money, I love it anyway, it's a boat and it whizzes along nicely and those are the two most important bits for me
I also like the size of mine (5.8m) because I can handle, launch and recover it single handed with relative ease now I have had a bit of practice, and without getting my feet wet (well maybe 6 inches of water at most - ordinary welly boot depth anyway). I'm not sure I could do that with anything much bigger, but then I've only been doing it for six months so maybe I will get better at it
This is basically a distilled version of what I have read over the last six or eight months both before and after getting my first RIB so you should probably wait a while and see if anybody violently disagrees with it before taking any notice of me