setting new prop width

billb · Post by **billb** » Mon Sep 28, 2009 7:25 am

sbeer: so what did you finally end with as far as props go I am wanting to change my fuel settings on mine to 320 HP what brand are they? I have 21x22 right now Thanks

sbeer · Post by **sbeer** » Thu Oct 08, 2009 6:14 pm

I set my props to 21 22 1/2. I get 2900 plus at wot loaded but lost my speed. fully loaded I run at 22 1/2 knots. Don't like it. used to get 24 knots. I am going to change them to 21 23. That should get me 2850 wot and at least 23 knots at cruise. I have been running the boat this year at 2450 to 2500 rpms. Sounds great and I get my 24 knots but I want to get it back to 2400 rpm at 24 knots. I had the bottom blasted the beginning of the year 7 coats of barrier 2 coats of paint and I don't even want to get into the blister repair. I can tell you this the yard I did it in said after I was done that he wanted to send all his pox jobs to me. NO THANKS. never want to see another bottom of a boat again. Mike

billb · Post by **billb** » Fri Oct 09, 2009 5:03 am

Mike: so 21/23 right how about any cup? thanks

sbeer · Post by **sbeer** » Fri Oct 09, 2009 2:13 pm

i have a 3 inch cup rifght now. i dont know if 5 inch will do it. what do you think more cup or the half inch in prop

franklyprice · Post by **franklyprice** » Fri Oct 09, 2009 2:56 pm

Different prop manufacturers use their own terminology to describe cup but I've never heard it described in inches. Regardless, I run 21 X 21 with .030" cup Acme's , wasn't happy with the top end or the cruising speed. Acme went up to .070" ( I believe) cup . End result was I gained about 1.5 knots at cruise to give me roughly 24 and top end went from 29 knots to a strong 30 to 31 knots with no decrease in WOT rpm's. I would consider adding a little more cup if I were you.

sbeer · Post by **sbeer** » Sat Oct 10, 2009 5:44 am

21 x 21 props and 24 knots, man thats great, I am not sure about the cup, but I did put a cup in my gasers when I had my 26 mako and it was a big mistake, alot of vibration. Had to take them off under the water. How can you decide on the cup. I want what frank has. If I keep my 22" and add more cup I should be even better than franks #'s. Agree or no.

franklyprice · Post by **franklyprice** » Sat Oct 10, 2009 2:45 pm

Mike, Acmes have a rake to them and this may help the numbers a little, therefor you may not get exactly the same performance. I had originally asked for 21 X 22's but he convinced me to run 21 X 21's because of there supposed efficiency and he felt if I needed more it would be easier to get it with more cup. Still wish I had started with 21 X 22's but it does go OK. I have to say though, in reverse it vibrates too much for me and the extra cup seemed to make it worse. Otherwise they are as smooth as can be . Sometimes I wish I had 4 blades for the reverse... As far as yours go, I'd take them to a decent shop and tell them what you want as far as performance goes and to add a bit more cup. Either that or buy some Michigan DJX's and get them 21 X 22 with a medium cup, like Doug and Bill ..Pretty much a given for performance.