what prop

[lotsaknots arnie]

i have a1980 s27 w/ms8 yanmar 3/4 in shaft, 2 bladeprop info on pitch ect. not visibal on prop.how can i find info to replace w/ 3 bladed prop?email adress lotsakots@aol.com thanks

 

[Steve Dion]

Have your prop shop determine the prop.

Arnie:Do not use your old prop to determine you new prop. If you are going to switch let the prop shop determine what 3 blade to use. If you take your old prop off they can tell you what you had. The rule of thumb for a 2 blade to 3 blade replacement is that you would either reduce the diameter by 1" or decrease the pitch by 1 degree.You need to give your prop shop the weight of the boat, the engine horsepower, max rpm rating, cruising rpm rating, transmission reduction ratio and they will give you the correct prop. If you tell them which prop, it's your problem if it is wrong.

 

[Kevin]

Prop shop

Dear Arnie,A propeller shop has a measuring divice which be used to determine the current pitch the propeller has in it. With the two blades pitch figured out, I would reduce the pitch by 1 full inch when replacing it with a three blade. Try if possible to maintatin the current diameter due to the fact the propeller is turning so fast.Hope this helps Kevin