1985 Mariner prop pitch?

[catfished]

I'm putting a 20 hp Mariner on my 14 foot MirroCraft Deep Fisherman aluminum boat that weighs about 200 pounds. Can you suggest a pitch for average use? My wife and I's total weight is about 450 pounds. We will probably have another 75 or so pounds with gas tank, fishing gear etc. My previous engine (15 hp Evinrude) planed us fairly well with what was probably a stock prop that came with the engine. The mechanic that I'm purchasing the engine from says a pitch of 14 should do it but I thought I'd get a second opinion since he's not that familiar with small outboards.

 

[steelespike]

Re: 1985 Mariner prop pitch?

Start with the prop that is on there.I couldn't find a 1985 Mariner though my repair manual does show a 85 20 hp. as well as 76-79.I'm not an expert but it seems to me a 14 in. is toward the high end of the selections I found for mariner 20s.12 seemed to me to be better for your load.But you shouldn't pick a prop until you run what you have and check the rpm.
I did finally find a motor/boat/load calculation;for speed non water sports application for Rascal props it suggested 10 1/8 X 13.for water sports 10 1/8 X 11 the 10 1/8 seems big to me.Prop selection here at iboats were all around 9in. diameter.

 

[catfished]

Re: 1985 Mariner prop pitch?

Thanks for your reply steelespike. The prop that is on there is a 4 blade and is cracked to the point of being totally unusable so I can't try it. I ordered the cheapest 14" aluminum from Solas via this site before I read your reply.:redface: Hopefully it will work out. I'm keeping my fingers crossed. Thanks again for taking the time to reply.