kagallag
New Member
I have about 10mm clearance between my prop tip and hull at the top of its swing. Does this seem like a potential problem ?
prop clearance
- Thread starter kagallag
- Start date
sailorman
Well-Known Member
what Dia prop
kagallag
New Member
15 inch 2 blade fixed
sailorman
Well-Known Member
Tranona
Well-Known Member
Simple answer, no as per sailormans reference. Even a 12 inch prop would be marginal
ebbtide
N/A
Boat came with prop which met designer & builder specs but after years of poor performance it took a specialist to identify the problem: insufficient clearance under the counter.
Andrew Childs from Clements Marine is your man.
tel 01234 378814
Andrew Childs from Clements Marine is your man.
tel 01234 378814
kagallag
New Member
thanks,
apart from the performance was there any other risks associated with poor clearance ? Incidently how little clearance was there with yours ?
apart from the performance was there any other risks associated with poor clearance ? Incidently how little clearance was there with yours ?
PetiteFleur
Well-Known Member
When I re-engined recently, after speaking to several prop people I fitted a 13" prop which only gave 1" clearance to the hull. The prop fitted when I got the boat was also 13"Ø LH but was brand new and had never seen water. I had to fit a RH prop when I fitted the new engine. Seems to work well, gets up to hull speed at below max revs. so I may have the pitch reduced by an inch when I should get max. revs.
boatmike
Well-Known Member
It is as others have said less than the ideal minimum. However I have seen many props with this sort of clearance work OK and if it ain't broke don't mend it. A hydrodynamicist would give you arguments to increase it based on the hulls interference with the pressure wave around the prop but there are only 2 things that matter really. "Does it drive the boat along OK?" and "Is there any scouring of the hull?" The latter will be evident by the antifoul being worn away in that area.
My guess is that moving the shaft down is such a pain that it's not worth it and fitting a smaller prop would reduce the blade area and slow you down anyway. The only other possible problem is a jam with something lodging between the prop and hull but this can happen anyway even if the clearance were increased. So if it works OK get on and enjoy your sailing.
My guess is that moving the shaft down is such a pain that it's not worth it and fitting a smaller prop would reduce the blade area and slow you down anyway. The only other possible problem is a jam with something lodging between the prop and hull but this can happen anyway even if the clearance were increased. So if it works OK get on and enjoy your sailing.