scorpion props

[gtflash]

looking for some more speed from my 7.5m 200 opti scorpion.

Currently running 21" laser and getting 43knots consistently, sometimes a little more sometimes a little less!

Was thinking about a slightly bigger prop but dunno if it will effect the planing speed too much (no tabs) or what sort of gains ill get!!

Whats the fastest 7.5m scorpion out there?? whats he running?

thanks

[Chris]

Originally Posted by gtflash

looking for some more speed from my 7.5m 200 opti scorpion.

Currently running 21" laser and getting 43knots consistently, sometimes a little more sometimes a little less!

Was thinking about a slightly bigger prop but dunno if it will effect the planing speed too much (no tabs) or what sort of gains ill get!!

Whats the fastest 7.5m scorpion out there?? whats he running?

thanks

7.5 metres is a big boat to push along I would say that at 43knots you are probably not far off the maximum you will be able to get with 200HP, however would Scorpion not be able to advise you if you can get more? They probably have been through this process dozens of times with similar setups.

[Zippy]

We had 52 kts from our 7.5 with 225 opti. There was a little tide with us at the time!

We would reckon top in normal conditions would be 48 / 49 kts. i think that was a 21" laser also.

[MarkM]

Scorpion 7.5 with Evinrude 250 DI, prop SST 23".
Topspeed 102 km/hr = 55 kts, reached it ones. Hardley any fuel and alone in the Scorp.
More often 98 km/hr = 53 kts.

[Ferdi]

Originally Posted by gtflash

looking for some more speed from my 7.5m 200 opti scorpion.

Currently running 21" laser and getting 43knots consistently, sometimes a little more sometimes a little less!

Was thinking about a slightly bigger prop but dunno if it will effect the planing speed too much (no tabs) or what sort of gains ill get!!

Whats the fastest 7.5m scorpion out there?? whats he running?

thanks

how are the revs at 43 kn ? are you in the recommended rpm-area ?

if revs are at the top of the recommended range then a 23" prop ( maybe laser or ballistic ) should give you a little more speed.
If you are at the lower end of revs with der 21" laser, a 23" probably will not give you more speed.


regards,
ferdi

[Daniel]

PM Richard B, he has a similar setup (Scorp 7.5 + Yam 200 HPDI) and i recall him playing with props some years ago. Infact, i recall one of those props failing on the way back from Alderney once, but thats another story.

[gtflash]

dunno the WOT at 43 knots i didnt look stupidly! anyone know the WOT of a 200 optimax! ill give her a run this weekend to find out!

Spoke to Graham Jelly today and he seemed to think that was about the norm however more could be gained with props depending on revs!

[Richard B]

43kt is in the zone.

I find that anything over 40 is hard to gain, depending on load and sea conditions.

With the Yam 21" prop, riding solo with hardly any fuel and a very choppy sea I once got 48kts but it took many miles of working up to this and trimming up bit by bit. Took me from Calshot to Yarmouth to get the last four knots with the RIB airbourne for a considerable amount of time. Never achieved anything like this in a flat sea, except with the Solas 19" which allowed 46kts on a flat sea hitting max revs. Then, as Dan points out, it fell off!

[gtflash]

hi guys! went out last night and seems to pull about 5000rpm! very nose up in all fairness below 20ish knots ended up stood on tiptoes to see all the drunken bums