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Old 24 May 2010, 07:26   #1
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Country: UK - England
Town: sheffield
Boat name: emm
Length: 3m +
Engine: 25hp
Join Date: May 2010
Posts: 3
Trouble planing

Hi I have a 3metre solid hull rib with a mariner 25HP engine, it is really fast and great fun but it takes ages to get on the plane and if only one person is in the boat its nearly impossible. I was wondering if it could be the pitch of the prop as i need to buy a new prop any way and thought getting a certain pitch could help me out. any help would be greatly apreciated
Thankyou
rick
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Old 24 May 2010, 07:50   #2
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Country: UK - Scotland
Boat name: Wildheart
Make: Humber/Delta Seasafe
Length: 5m +
Engine: Merc 60 Clamshell
MMSI: 235068449
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Firstly, welcome to ribnet!

I guess we're talking nose in the air, and not a lot of forward movement? That could be down to one or a combination of factors -

- weight too far aft
- engine trimmed to high
- prop pitched for top speed rather than accel.

Before you messa round with new props, try playing with the engine trim. Not sure if you manual or power, but if manual, drop it in towards the transom hole at a time & see what happens. If power, tuck it full under & once on the plane back it out again. (And check your "manual stop" pin is not at the outermost hole)

Weight distribution - move something heavy forward (on a 3m even lean yourself over the wheel may be enough or "jump" on the floor to force the bow over it's own wave) If you;re on tiller, shuffle forward as far as you can get.
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Old 24 May 2010, 07:57   #3
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Country: UK - England
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hey

thanks for the reply and yes I mean nose in the air, it is manual tilt and tiller control, it is fully dropped to the bottom and i have my brother or friend leaning over the front this does get the nose down and it goes like a rocket once there, when on your own however it is nearing impossible to get the nose down, as I need a new prop I thought I could try it but I have no idea of the pitch I would need. the Engine is a 2 stroke mariner 25hp 1999
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Old 24 May 2010, 12:41   #4
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Country: UK - Scotland
Boat name: Wildheart
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if you're trimmed right in, have you tried both of you as far forward (along with fuel tank etc) then creep back once on the plane?

What pitch you got at the moment? will likely be stamped somewhere on the hub
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Old 24 May 2010, 12:57   #5
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Country: UK - England
Town: southampton
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dolfins might help you get your arse out of the water,
if not give this a read
http://www.allinflatables.com/shoppi...ers/index.html
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Old 25 May 2010, 07:15   #6
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Country: UK - England
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Engine: 25hp
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hey guys thankyou for all the help ive decided to go for getting a set of Doel fins by the looks of things they seem to of helped others in my situation if any one has any experience with them please let me know before i buy them If not ill post after next week with how they went for me
thanks again for the help
Rick
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Old 25 May 2010, 07:17   #7
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Country: UK - England
Town: Up Norf
Make: Avon SR4,Tremlett 23
Length: 4m +
Engine: Yam 55, Volvo 200
Join Date: Apr 2007
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What RIB is it?
My mate had a 3m RIB and with a 25hp engine, it planed with him on but with two of us we both had to hang over the bow to get it to plane.
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Old 25 May 2010, 18:12   #8
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Country: UK - England
Town: Dorset & Hants
Boat name: Streaker/Orange
Make: Avon/Ribcraft
Length: 4m +
Engine: 50Yam/25 Mariner
Join Date: Apr 2007
Posts: 5,551
Quote:
Originally Posted by rickdugdale View Post
hey guys thankyou for all the help ive decided to go for getting a set of Doel fins by the looks of things they seem to of helped others in my situation if any one has any experience with them please let me know before i buy them If not ill post after next week with how they went for me
thanks again for the help
Rick
Rick I have a 4m Avon that is very stern heavy, with 50hp on it it wasn't a problem with power to get it on the plane, but in doing so was very bow high for a few seconds until it got over the bow wave.

The doel fins sorted this out brilliantly - I lost a couple of knots off top speed but was more than happy with this as a trade off.

Before ftting them I'd think very hard as I have also had a 3m Avon Rib that planed easily with 8hp with 2 on board - so something isn't right with your set up ! Maybe its just far too much weight in the stern for the boat.

I'd take the prop off & take it to someone 'in the know' to see what pitch it is and see if you can borrow a a lower one to see what happens.

Pete

Pete
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Old 26 May 2010, 08:38   #9
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Country: UK - Scotland
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A 25 could weigh up to 75Kg if it's a downrated 30. That's prety much like having an average sized someone sat on your transom.
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