laser II question

[glen76]

what are the pros and cons of laser II props! mercury says its high raked for greater lift!! is that bow or stern lift??

[Burty]

bow

[Cookee]

But not as much bow lift as something like a Raker

[glen76]

does bow lift mean more speed?? manufacturer of boat seems to think theyre not to great with a laser and ive found anything more than 1/3 trim and grip starts to break away! so if i had a non bow lift prop could i use more trim and maybe gain more speed or does it not work like that

[Burty]

i doubt it cus more trim would then give you more bow lift so back to square one.
Anyway loose is fast!

[Cookee]

Originally Posted by glen76

does bow lift mean more speed?? manufacturer of boat seems to think theyre not to great with a laser and ive found anything more than 1/3 trim and grip starts to break away! so if i had a non bow lift prop could i use more trim and maybe gain more speed or does it not work like that

When you say the grip starts to break away what do you mean?

[glen76]

the prop looses grip, the engine will start to over rev a little with no gain in speed just a little more noise

[Cookee]

Originally Posted by glen76

the prop looses grip, the engine will start to over rev a little with no gain in speed just a little more noise

Sounds like it's just overtrimmed - is it a stepped hull, what size hull, height of prop shaft compared to the bottom of the transom, what revs are you pulling, and finally what speed? If it's a stepped hull it will do that because you're fighting the steps and that won't work!

[Jon Fuller]

Originally Posted by Cookee

If it's a stepped hull it will do that because you're fighting the steps and that won't work!

Unless they're 'rocker' style steps, like many yank designs have, unlike the stuff we see a lot of here (Ocke, etc) the rocker style steps still respond to trim.

However, the boat listed in his user profile is a Scorpion, so the chances are it's non stepped.

[glen76]

Originally Posted by Jon Fuller

However, the boat listed in his user profile is a Scorpion, so the chances are it's non stepped.

correct... its 7.5m hull length scorpion NON stepped hull. 200 optimax, pulling 5000rpm at 43knots on average.....

Came back from cowes last nite... water was crazy and had littlin on board so took it easy but cant get the nose down under 20 knots so cant see sod all!!

Manufacturer says trim tabs essential on em. but also that laserst dont work on em that well.......

its quite a deep v but id like more trim control and more speed....

[Jon Fuller]

The highly warped hull design of the Scorpion should should plane with little of the 'getting over the hump' seen with more constant deadrise designs and it should certainly plane at a lower speed than 23mph.

Are you sure there isn't too much weight aft? or that there isn't water trapped beneath the floor in the back end somewhere?

Dunne make sense.

I would have thought the trim tab suggestion is for levelling rather than keeping the bows down. It really shouldn't need that.

My money says there's water trapped neath the floor.

does it by chance have a 25" leg? (XL)

[glen76]

Originally Posted by Jon Fuller

does it by chance have a 25" leg? (XL)

dunno ill check!!

[glen76]

so how do i know what size the leg is!! only identifier i could find was this sticker!! can i measure it?

the engine is on lowest hole also and the centre line of prop sits about 4-5" below keel

[Jon Fuller]

I think that's a 20" (200L = long)

As I said, my money says you have extra weight in the stern you don't know about.

[glen76]

Originally Posted by Jon Fuller

I think that's a 20" (200L = long)

As I said, my money says you have extra weight in the stern you don't know about.

ok thanks jon

ill look into it

[gazza]

http://www.boattrader.com/listing/20...TIMAX-86544746

Looking at this Part Number on this one thats for sale would suggest Jon is correct.

gaZ