O/B Weight Differance
 

Hi
Can anyone tell me how much the weight of an outboard would have on performance on a 5.5m rib .For instance an E-tec 75 weighing in at 145kg verses an Optimax 90 or Honda 90 at 172kg . Would the extra 15 hp be lost due to the extra 27kg weight ?

Would a Destroyer/Oceanpro be under powered with an E-tec 75 ?.
Thanks
Tim

I wouldnt have thought not, with the right pitch prop it would be a good motor for this size. Our club Delta had a Mariner 75 on and it went well, all be it a bit sluggish with 6 divers but then thats getting close to its designed payload.

Before power is considered do have a look at the transom rating it should be in both engine weight and max hp. Not a good idea to go over this but people do.

To put the weight difference into perspective, its about 36 litres or so of fuel.......

The difference is with fuel you can (if it's in a nice 30L plastic tank) put the weight in a sensible place to trim / balance the boat. But on a RIB that weighs in the vicinity of half a ton, probably make next to no difference

Why not an Etec 90?

Its a second hand rib . Looking for something around the 5.5m with around the 100 hp etec,opti or 4 stroke and wondering if a 75 etec would be much down on performance . Usually go out with two mates both with 5.5m one with a 100hp 4st the other with a 85hp 2st and just want to make sure that I will be able to keep up to them :D

the etec 90 is the same as the 75 .

I tested a demmo of my 5.5 m boat with a 75 etec and it went OK with 2 aboard but i felt it could have been a bit sluggish when loaded .

the 90 had a good bit more punch and is the lightest in its class. I made my decision as much on the wieght as anything else as i feel it makes a fair difference when you can save 30 ish kilo hangin on the transom . The dealer also agreed he had tried the same boat with heavier motors and said it didn't feel as balanced or perform as well .