Humber Rib repower

Martin · 08 June 2004, 22:46

Bit of advice please. I have a Humber 6metre destroyer rib with a 90hp, but I want to get a larger enngine on it.

Budget dictates two stroke so is it a Yamaha 115 or 130 hp.

Does anybody else have a similar boat with either of the above engines on to give me a rough idea of realistic speed achievable.

Thanks in advance

Martin

The Jackeens · 08 June 2004, 23:04

P

Nick Hearne · 08 June 2004, 23:06

Quote:

Originally Posted by The Jackeens

P

You been at the sherry again?

gingercoastie · 08 June 2004, 23:42

Quote:

Originally Posted by Martin

Bit of advice please. I have a Humber 6metre destroyer rib with a 90hp, but I want to get a larger enngine on it.

Budget dictates two stroke so is it a Yamaha 115 or 130 hp.

Does anybody else have a similar boat with either of the above engines on to give me a rough idea of realistic speed achievable.

Same question as above but I am thinking Suzuki 140/200hp on a 6.3 Ocean pro.

Martin hope you don't mind me jumping in on your thread.

jwalker · 09 June 2004, 00:43

I had a Destroyer 6.5 and it had a few motors in its life. 200 Mercury, 150 VRO Johnson and, latterly, a 200 Suzuki. The Suzi was the best by far, in all respects, and it's midrange power leaves the others floundering.

CJL · 09 June 2004, 09:56

I`ve got a 5.5 Humber which is spec`ed for a 135. But the guys at Humber beefed up the transom and they put a 150 Optimax on it cause its the same block size.

My speed to other day with 6 on board fully fueled was 42.6kt

With very little fuel and just one i`ve pushed 48kt. One ripple tho and it goes pete tong!

Chris

Pete7 · 09 June 2004, 10:35

Quote:

Originally Posted by Martin

Bit of advice please. I have a Humber 6metre destroyer rib with a 90hp, but I want to get a larger enngine on it.

Budget dictates two stroke so is it a Yamaha 115 or 130 hp.

Does anybody else have a similar boat with either of the above engines on to give me a rough idea of realistic speed achievable.

Thanks in advance

Martin

Martin, I had a 5.95 Osprey Viper with 115 v4 Yamaha. Top speed was 38 mph with 17" prop and four divers + kit on board. It would handle a 19" prop lightly loaded but rarely ran it like this. Fuel was 8 gph. Good engines by the way.

Pete

CJL · 09 June 2004, 11:15

Go for an OptiMax.

I`m blown away at the fuel economy. The pick up is mind boggling.

Down side is they are expensive to service. The yamaha's I`ve used seem to burn a lot of oil in comparison but they keep going going and going. All with no problems.

You do pay a premium for the Yamaha's and the Optimax has a 3yr warranty for less wonga.

Horses for courses.

Chris

Alex Brown · 09 June 2004, 12:22

Quote:

Originally Posted by Martin

Does anybody else have a similar boat with either of the above engines on to give me a rough idea of realistic speed achievable.

I too have a 6metre Destroyer but with 140 Suzuki 4-stroke on it. Max speed is just on 43 knots, 2 people up and full of fuel. 9 people with lunch kit etc... slows that down to 33 to 34knots.

At WOT in choppy conditions it's a hold on tight situation, but the boat still feels secure. Slow down to 35knots, and everything gets far nicer and you don't have to hold on so tight.

Fuel economy is great, 4-stroke isn't the fastest engine to get to top speed, and I dare say it would probably be on par just about with a 130 2-stroke engine for top end speed.
I generally cruise between 25 and 35knots depending on conditions, and the boat is very comfortable in this range and the engine doesn't seem hassled in any way.

-Alex

Nick Hearne · 09 June 2004, 14:37

Martin how about this from http://www.waynemaddoxmarine.co.uk/

"While stocks last we are offering the Mercury 150HP OPTIMAX L WITH SMART CRAFT GAUGES & LASER II S/S PROP

for only £6999 00 INCL VAT"

Now how do I persuade the wife that we knead one?
Nick

Headhunter · 09 June 2004, 16:39

Martin

I have a Humber 5.5 Destroyer with a 130hp Yamaha 2 stroke.

Top speed with light load so far 43 knots, with waves no more than a foot. A small chine walk began to develop so I will be making a few small adjustments. With flat water I expect there is some more speed say 45-46 knots.

It's early days with this set-up but the max speed achieved with the same load from our Johnson 90 2 stroke prior to the upgrade was 38.6 knots.

Both engines had a 19 pitch prop.

Where the real difference is noticed is in sheer power when accelerating.

Hope this helps.

John

timboli · 09 June 2004, 20:10

"A small chine walk began to develop so I will be making a few small adjustments".

What adjustments wiill you make?My assault chine walks when trimmed right up at the bow if there are any notable waves and WOT(about 40 knots),I have a 21" propeller,and the engine pulls 6000-6100 revs,I was thinking of getting another propeller of the next pitch up for economy if nothing else.Will this make any difference to the chine walking or should I just not trim up so high?The chine walk disappears as soon I trim down or back off the throttle.
The engine WOT range is 5000-6000,the dealer says I should keep the prop I have as the engine should run as close to 6000 rpm as possible.

Headhunter · 09 June 2004, 20:36

I am told by my engine service man that the trimtab is the first place to look.

John

Rogue Wave · 09 June 2004, 20:52

Hmm Optimax! They really are a good unit and so cheep to run.

Martin · 09 June 2004, 21:04

Thanks for all of the suggestions. Having spoken to a couple of engine guys today I might stretch my budget a bit more so its between four stroke and new tech two strokes, but I do not want to start a debate on that front I am sure that there are plenty more threads on that!

150hp optimax sounds great, but may be just too much power.

What I want to do is cruise comfortably at 30 kts and push towards 40kts occasionally, whilst keeping some degree of economy. There is no point putting too much power on the boat as there are few times when the conditions allow you to run fast for extended periods.

Mmmm must keep pondering on this one. Any more suggestions appreciated.

Martin

jwalker · 09 June 2004, 21:21

Quote:

Originally Posted by timboli

....or should I just not trim up so high?The chine walk disappears as soon I trim down..

There's your answer. Just a tad will increase the waterline length and bring back the stability.

Make sure you have NO play in the steering and/or bearings and the engine mounts must be good.

--------------

Quote:

Originally Posted by Martin

...150hp optimax sounds great, but may be just too much power...

Nope, 150 will be good.

Martin · 09 June 2004, 22:43

Any ideas what fuel consumption is on a 150hp Optimax? I know it will vary depending upon sea conditions, load etc, just after rough estimate.

Martin

The Jackeens · 09 June 2004, 22:48

Quote:

Originally Posted by Martin

Any ideas what fuel consumption is on a 150hp Optimax? I know it will vary depending upon sea conditions, load etc, just after rough estimate.

Martin

this link http://www.yamaha-motor.nl/products/...ws/article.jsp
which I posted on another shows consumption in relation to other 150 ies

not as good as the 4 strokes
hope it helps

P

Martin · 09 June 2004, 22:55

Thank you, I will look now.

Martin