Max speed

FreeTrader · 06 April 2006, 20:10

Hi all

Out today in unbelievable FLAT calm at lunch time. Belted down to Minkies and saw scores of dolphins. Was very difficult to go back to work...

Anyway on the flat was the first time I'd had a chance to experiment with Quick Exit's max speed. At 5500 rpm the 225 Opti maxed at 42 knots. I wondered what the max rpm was, and what you guys think the max speed should be for a Scorpion 8.5?

I tried lots of combinations, with the prop just about cavitating etc., trim tabs down and up, but still couldn't get past 42.

42 knots was the SOG from the GPS, the paddle said 45, so we'll go with the gps!

Any thoughts?

Phil

Alan · 06 April 2006, 20:21

Quote:

Originally Posted by FreeTrader

42 knots was the SOG from the GPS, the paddle said 45, so we'll go with the gps! Phil

So presumably a 3kt tide then?!

42kts for 8.5m Scorp/225 seems in the right ballpark Id say. Wide Open Throttle range for a 225Opti is 5000-5750 so you are bang on there. My (now Richard B's) 7.5m Scorp/200 Yam I think maxed out around 45kts.

qcamel · 06 April 2006, 21:06

My 8.1 Scorpion runs the 225 optimax, however she has a stepped hull but will achieve about 54 knots and that is running a 4 blade steel developments 21 prop. Revs are at about 5300 at that point.

Ollie

Actionboat.dk · 06 April 2006, 21:24

Hi Phil
Calm water is realy not for the Sco. it is a deep v hull. and will not go as fast in calm as in 30-40cm waves.
Is it water all the time or on trailer?
I will say 45-46kn as your max with a clean hull??

BR Jan

FreeTrader · 06 April 2006, 22:01

Hull is clean, she's on a drying mooring in St Helier's old harbour. The mud keeps her free of fouling.

Matt · 06 April 2006, 22:13

Excuse no 53 why a boat runs slower on windermere than the sea.

Quote:

Originally Posted by Actionboat.dk

Hi Phil
Calm water is realy not for the Sco. it is a deep v hull. and will not go as fast in calm as in 30-40cm waves.
Is it water all the time or on trailer?
I will say 45-46kn as your max with a clean hull??

BR Jan

karlT · 07 April 2006, 09:38

Glad to hear there are loads of dolphins around already. Here are a few stories about dolphin watching by our local States crews! What do you think??

The States of Jersey new £5million tug was down Les Minquiers about 2 months ago when they struck an 'uncharted' rock. I have heard that they were actually following some dolphins at the time and were not exactly where they thought they were at the time. (hence the rock has been there and known about for a long time).

I also heard form someone on the boat at the time about 3 years ago that HowardLe Cornu (Harbourmaster) in one of his jollies with the old custons boat also blasted off down near the Minquiers to see some dolphins only to slow rapidly before realising he was approaching some rocks that were awash.

That is the same harbourmaster that drove the 8m avon straight across the stern of a 6m tornado and nearly killed a few people then blamed a faulty trim. (he was apparently trying to soak the other boats crew, caught the wake and lost control) ??? If the trim had failed and boat was being driven sensibly to start then the collision would never of occured.

Interestingly this same rib was bought by a private owner last year who with his child fell out without killcords and boat raced up the wall at Elizabeth marina narrowly missing a number of other craft in the bay.

Dirk Diggler · 07 April 2006, 09:44

Quote:

Originally Posted by MadMat

Excuse no 53 why a boat runs slower on windermere than the sea.

You bad boy!

Jono · 07 April 2006, 10:09

Personally, I always prefer excuse 54…. “Then engine’s still in bits in the conservatory……”............

FreeTrader · 07 April 2006, 19:28

Karl, I saw that rib run-up Elizabeth marina. Quite a sight: I wish I'd had a camera.

It was a mate of mine who owned the rib. It was over engined then (2 x200 Evinrude), but he's re-engined with 2 x 225 Evinrudes, so that's sensible?

He didn't have the killcord on, but now has one of those wireless ones on.

IMHO that hull is not right.

BTW: was out today with a mate who felt we might get an extra 5 knots by moving the opti 2 notches up the transom - what do you guys think?

qcamel · 07 April 2006, 20:02

Tickled Pink engine was set very high, great for top speed tends to cause mild cavitation when manouvering in a chop or when turning and applying power from a standstill. Also means that you lose an element of control of the bow as there is less effect caused by tilt and trim. I have had jacking plate fitted and will see trial on Wednesday. Hope this will allow top speed and low speed control, fingers crossed.

Ollie

Matt · 07 April 2006, 20:54

No longer.

Quote:

Originally Posted by Jono

Personally, I always prefer excuse 54…. “Then engine’s still in bits in the conservatory……”............

Roy Smith · 07 April 2006, 21:27

Had the same probleam with our Scorp first sea trails max 40 kts GPS
tried heeps of props, cavatation etc,etc
Graham then droped the engine down,23 inch prop 49.9 knts three up half tank never got the magic 50 but it was with a standard prop.

Charles · 07 April 2006, 22:21

Quote:

Originally Posted by FreeTrader

BTW: was out today with a mate who felt we might get an extra 5 knots by moving the opti 2 notches up the transom - what do you guys think?

Don't waste your time doing this, what's wrong with circa 40knts?

Roy Smith · 07 April 2006, 23:13

isant that what we buy the Scorps for Speed and handling