Adjusting Prop Pitch?????

BobM · Feb 23, 2010

If they can do it I can't see why not. They can balance the whole thing too. Is there a problem with the current pitch?

druid · Feb 23, 2010

Usually - yes. Changing by an inch is usually no problem, and if the prop is fairly standard, any prop-shop can do it. HOWEVER, they do tend to look at it, and if it's in bad shape (galvanic corrosion turns bronze into cardboard), they might refuse to do it.

It's usually best to send it to the mfr, even if it's "standard". Campbell Sailor will repitch a prop in about 3 days: one day to send it to Nanaimo, one day to repitch, one day to send back. Comes back nice and shiny, and total cost is about $80 including shipping. Course that's from Vancouver...

druid

Ross · Feb 23, 2010

Woodster, I bought a 13x15 three blade for my boat and it was just too much pitch. I took it to a prop shop and he repitched it to 13x13 straightened it. he said that it ranged from 15 inch pitch on one blade to 14 on another and something in between on the third. Then he pointed out to me that it started life as a 14x15 and had been cut down. He told me that 2 inches is about the limit of pitch change that he can make.

Hermit Scott · Feb 23, 2010

woodster-I have 3 props that I bought on ebay, 2 new, one in perfect used shape. If you just keep an eye out, I have confidence you can find exactly what you want. As long as you are not looking for folding, feathering or Campbells sailor props, it's cheaper to buy them on ebay that to have them repitched.
I spent less money buying three props of different pitches to find the one I needed than I would have buying one prop and having it repitched once.
Some people's time is worth more than mine though. I don't have a job so I find myself with plenty of time to screw around with saving a few bucks on a prop. lol

Jalepeno · Feb 23, 2010

My CAL had a major overheating problem when I bought her three years ago. Investigation by Garthside Marine in Sidney BC (Yanmar shop) and communications with owners of similar boats found that the major problem was the propeller diameter and pitch. The previous owner had installed a three blade Campbell Sailor CS3LH13x9x1 probably in the misguided thinking of reducing cruising RPM and increasing reserve maximum speed. The no load governor limited speed was correct at 3200 RPM but in the water with a clean hull the Yanmar YSM12 could only get up to 2500 RPM (full load speed should be 3000 RPM) and would overheat after about ten minutes due to excess fuel. Speed over water was just under 7 knots while she tried to climb the bow wave and bury the transom (22 foot LWL = hull speed of about 6.5 knots). I switch to the spare two-blade Campbell Sailor CS2LH12x8x1 propeller for the delivery cruise to my homeport. The two-blade worked well but had a lot of reverse prop-walk. Campbell Sailor recommended reducing the three-blade to 12" diameter and 7" pitch (propeller shaft speed at max load should be 1518 RPM). They modified the propeller for CDN$50 (plus shipping) and now she can get the full load 3000 RPM and don't have as much prop-walk as the two blade. Campbell Sailor said that with their slim cupped propellers, one inch of diameter is equal to about two inches of pitch and one inch of pitch is equal to about 150 RPM. Also a two blade needs about one extra inch of pitch to make up for more slippage. I don't know if this is true for other types of propellers.
www.westbynorth.com/

redhead78 · Feb 23, 2010

prop pitch

Hey guys I was thinking about prop pitch and how it has to be properly matched and all. I am repowering, new everything, from trans, shft, stuffing box. The shop knows the boat displace, and trans ratio, engine HP, and he tells me his prop guy can match the correct prop to the boat. Only problem I see if not , I have to haul the boat? Who is that on ?? me...I have no exp with this whats the chance he will get it right, I think he knows his boats, I trust him. Any thoughts on what I should look for......Thanks Red

BobM · Feb 23, 2010

I'd try it if you are keeping your 2QM15

woodster said:
the prop is a 15/8 ...it fits my boat shaft and is the correct rotation .......the original one that was totaly gone except for the hub was a 15/9... and i am concerned that it may let the engin rev to high in RPM's...so i am planning ahead just in case....it is a two blade prop btw.....quote]

My boat has a 2QM15 and 16 RH 9 so ad 15 RH 8 might run okay with its lower surface area.

BobM · Feb 23, 2010

Should be fine.

paulhille said:
Hey guys I was thinking about prop pitch and how it has to be properly matched and all. I am repowering, new everything, from trans, shft, stuffing box. The shop knows the boat displace, and trans ratio, engine HP, and he tells me his prop guy can match the correct prop to the boat. Only problem I see if not , I have to haul the boat? Who is that on ?? me...I have no exp with this whats the chance he will get it right, I think he knows his boats, I trust him. Any thoughts on what I should look for......Thanks Red

From what I have read / seen the prop guys know their stuff and their recommendations are good. It is only when owners stare switching props around without paying attention. Think about what you want for a prop and then call a few other prop guys to see what they come up with during their free quotes. They should all be in the same ball park.

Don12364 · Feb 23, 2010

Check it Yourself

Go to the Castle Marine web site in Wales and download the prop calculator. It uses a well known formula and is probably the one your prop shop uses anyway.
Just plug in the data and see what the prog recommends. This will give you an idea of whether your guys know what they are doing or are among the 'smoke & mirrors' crowd.
The prog gives a useful starting point and also indicates the speed to be expected from your engine and your boat type. A benefit of going to a specialist is that, if the boat's performance is not quite right, they should be willing to change it without additional charge.

Have fun.

http://www.castlemarine.co.uk/pitch.htm

Hermit Scott · Feb 23, 2010

paulhille said:
Hey guys I was thinking about prop pitch and how it has to be properly matched and all. I am repowering, new everything, from trans, shft, stuffing box. The shop knows the boat displace, and trans ratio, engine HP, and he tells me his prop guy can match the correct prop to the boat. Only problem I see if not , I have to haul the boat? Who is that on ?? me...I have no exp with this whats the chance he will get it right, I think he knows his boats, I trust him. Any thoughts on what I should look for......Thanks Red

I would see if you can get a prearranged deal for 3 hauls if necessary. From reading of others finding the pitch for their boat, it takes a few tries.
(I am cost conscious, poor) so I dive and change it myself with out hauling. You probably need an ice pick where you are though.