What Speed Should I Expect From This Setup?

MAHA · 22 October 2007, 19:51

Advice please,

What speed should I expect from this.....................

7.5M Cobra with 225hp Mercury Optimax with stainless 21 pitch prop.

1 person, 25 Gallons of fuel.

Been out today in flat conditions & got 46 knots, don't know if this is good or bad?

codprawn · 22 October 2007, 19:55

Not bad at all - sounds like a nice setup!!!

Chris · 22 October 2007, 21:43

Did you trim the engine out for max speed?

Chris

Zippy · 22 October 2007, 21:47

seems pretty good to me. i get 49 from my 7.5 and same engine when trimmed right out.

Cookee · 23 October 2007, 09:32

Quote:

Originally Posted by MAHA

Advice please,

What speed should I expect from this.....................

7.5M Cobra with 225hp Mercury Optimax with stainless 21 pitch prop.

1 person, 25 Gallons of fuel.

Been out today in flat conditions & got 46 knots, don't know if this is good or bad?

What RPM is it pulling at that speed?

MAHA · 25 October 2007, 20:30

I think the RPM was about 4800.

The trim was 1.5.

Cookee · 26 October 2007, 13:40

Quote:

Originally Posted by MAHA

I think the RPM was about 4800.

The trim was 1.5.

Trim doesn't really mean anything as each boat is different, but I think you'll find it should be revving a bit more than 4800 - did you try more trim or could you move some weight towards the back of the boat?

By the way if you have a 1: 1.87 gearbox that's about 2% slip which is amazing - could you have had a little help from the tide?