Quest for Speed

[Fire99]

Hi All,

My Freeman 30 is now back running.
I've even done 2 (somewhat short) trips on my own and managed to
leave and moor back up at the marina solo.
I've also removed enough shingle, scrap iron et. etc. to do an
interesting garden display.
However, being a never satisfied kind of chap, Speed is very low
running on a pair of 50hp Lombardini 2004m engines. Since they've
only done 32 hours each so far, i'm only running them at 2400rpm out
of 3000 but im only getting 6.5 knots at this speed. (which funnily
enough is no better than when she had all that weight onboard)
There is some concern that the wrong props were fitted with the
engines but that remains to be proved.
Can anyone please indicate a) what the maximum speed i should expect
and b) what i would have to do to get to 10 knots.

Any advice is greatly appreciated.

regards,

Nick Wilson


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[hlb]

See what happens if you go up to 3000 revs. Either it wont get there, so wrong props, or it over revs, so props are to small.

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Haydn

 

[ChrisP]

Our Ferrman 30 was fitted with the Parsons Bedford diesels which were rated at about 98HP each. In standard trim she wouldn't fully plane and speed was about 10 - 12 kn. Fitting trim tabs and new props gave about 15-17kn with full fuel tanks and about 30 gallons of water. Our water tank was fitted between the engines but some had the tank right aft in the back cabin. This made a real difference to the speed and ride. The fastest ones had the bigger Ford's in them (108HP in stock trim). I have a nasty feeling that with smaller engines you may have a little trouble getting over the hump and onto the plane.

Good luck

ChrisP;o)

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[byron]

Sounds suspiciously like you are running the wrong props. Contact a prop firm, give them all the spec and they will advise you the techspec that you should have on.

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[Fire99]

Thanks Gents,

Due to tide times, i'll have to check flat out performance on Saturday.
I very much doubt she'll push past 10 knots with a pair of 50's..
I don't want to re-engine her though as the engines are new..
Lombardini do a pair of turbo's with about 89 hp each, the engines seem very similar. Not sure if the additional equipment could be bolted on..
But she is an old girl '66 ish so this may be a bit much.
Were all the parsons engines rated around the 90 hp mark?
The previous owner replaced the parsons engines and the survey said they were rated at 50hp..

cheers,

Nick


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