right prop ...?????

M

MaverickGrabber

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Apr 9, 2009
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1977 silverline nantucket 22vc with merc 228 i/o ..3240 lbs dry
not sure what it came with new.........when i got it.... it had a 21p.... only pull to 2600- 2700 rpm merc 228 gm 305cid.boats around 4200 lbs with me and all in it ......looks to me it should have a 15p-16p prop on it

thanks for help / thoughts
 
C

Cptkid570

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Oct 18, 2005
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Re: right prop ...?????

Before dropping all the way down to a 15 pitch, you may want to try out a 17 pitch. I think a lot of shops will let you test your boat out with their props as long as you ultimately buy one from them... or, maybe if you have a friend that has a mercruiser, you could borrow his prop.

Let us know what you figure out..
 
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steelespike

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Re: right prop ...?????

We could tell a little better whats going on if we had your max rpm and speed.
I would think at 2600-2700 your not even on plane.That makes the rpm meaningless
as far as any prop selection.As suggested don't get carried away.
If you could lighten things, maybe put a couple of people in the bow and get it to plane your rpm would be more helpfull.
 
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Cptkid570

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Re: right prop ...?????

well, your video should get you better responses than I'll be able to give. But, I once had a 26' boat that was underpowered with a 260hp 5.7 liter. The only prop that I could get any performanced out of was a 15 1/4 x 15. So, maybe you do want to try a 15 pitch..

How good does your motor run? Ever done a compression test to see if you are getting the most out of your engine? Is your carb a 4 barrel? Are the back 2 opening up and giving you gas?
 
M

MaverickGrabber

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Re: right prop ...?????

have not done a compression test was my uncles?he passed??. he got it in 1982 when it only had 50hrs on it ?he hit a rock and put the 21p on it ?did not care it took long time to move ?..the boat now has 234hrs on it ??been parked for years Engine runs good ?had to put a new carb on it ..Q-jet 4brl ..tune up
 
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Cptkid570

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Re: right prop ...?????

And you may want to check and see if your tachometer is correct. You know.. 26mph are 2700 rpms isn't bad at all.. the problem is how hard your engine must be having to work to get that 2700 if that is WOT.. Your engine will have an easier time spinning a 15 pitch prop... I'd recommend a 14 1/2 or 15" diameter if you go with a 15 pitch.
 
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steelespike

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Re: right prop ...?????

MaverickGrabber said:
cant lighten it up any with 77 gal of gas 2-3 persons and fishing gear ....boat dry is 3240lbs..........--with the 21p 26 mph @2700 WOT...took a long long time to get there.. I borrowed a 19p 3200 rpm @28 mph WOT.....takes a little bit to get there but a lot better then the 21p ....with the 19p
http://www.flickr.com/photos/maverickgrabber1972/4724396666/
Click to expand...
At 3200 your about 1400 rpm short. Trying to get that with a prop would put you at about 12". I'm pretty sure there is other issues."parked for years"Could have absorbed water in the flotation under the floor.Timing advance may not be working,Compression?
Fuel supply erratic/contaminated.Throttle plates not opening all the way.Bottom distorted from poor starage?Stringers under thre floor rotted allowing hull to flex under strain.
 
180shabah

180shabah

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4,995
Re: right prop ...?????

At 3200 your about 1400
Click to expand...

Actually only about a grand short (pre-roller has lower WOT) and he will gain MORE then the typical 200rpm per inch. He is not close to getting into the power band, it'll come "alive" as he gets closer.
 
M

MaverickGrabber

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Apr 9, 2009
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Re: right prop ...?????

the 228s max rpm 4200-4600 im thinking a 16p will do the trick ....just need to find someone with one so i can try it
 
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