O/B Weight Differance

TimMcC · 11 February 2008, 13:49

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

Simon B · 11 February 2008, 14:46

Quote:

Originally Posted by TimMcC

Hi
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.

9D280 · 13 February 2008, 09:51

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

Nos4r2 · 13 February 2008, 10:33

Why not an Etec 90?

TimMcC · 13 February 2008, 14:03

Quote:

Originally Posted by Nos4r2

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

ian parkes · 13 February 2008, 23:32

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 .