prop survey

RAP, not sure on RPM's, tach not working correctly, shows only about 3300 at WOT. I've got a couple electrical gremlins I'm tryin to work out.
 
I have an 85 merc 150 on mine and since I am quite fond of running up on shoals and oyster bars as well as getting stuck at low or wind tide where I have to chew my way back into deep water , I now only run a 4 blade comprop.Its a 13.7 x 18. Sand eats up aluminum very quick and they are not cheap to fix. You can get 4 blade comprops on ebay for 20 or 30 bucks and if you bust off a fin just throw them away .I cant go fast down here anyway because of the shallow water shoals and the sloppy ocean conditions most of the time. I tested the speed in the intercoastal a while back with a hand held GPS and it showed 37 with me , my dog and a full tank of gas and I have bottom paint ..Frank
 
reelapeelin said:
Gotcha, Tin...is the tach adjusted to the motor it's presently hooked up to?... ???...
Click to expand...


Not sure...I don't see any settings on the back of Tach. Boat did have a Force 150, is that a 4-cylinder? Maybe that's my problem???
 
Stock Aluminum prop on '75 135 HP Evinrude, 13x19, hitting 4800RPM max and 38MPH (GPS), two people, 3/4 tank ( 45 gallon capacity). Yesterday ordered new 13 1/4 x 17 to try to get a little more RPM's.

But, from reading boards, looks like link and sync might be all that was needed, or might need to do in addition to prop. Is that a simply task to perform?
 
Tin, what mfgr of the tach (Teleflex or who?)...there should be a slotted plastic screw-head flush w/ the back of the tach's case w/ small markings at the different settings...you might have to shine a light in there to see it...

Sfprovyn, what is tach showin' at 37 mph?...for a 150, I'm thinkin' you got some more performance that small dia. and 18 pitch prop ain't geetin' for ya...IMHO, these heavy V20s need a larger dia. prop as I tried several and got best from a 15 1/4" dia. ;) ...and keep in mind that the wrong prop will overwork the motor and shorten life, not to mention a negative fuel efficiency... :-/...
 
I dont have a tach so I dont know about the RPM's. A friend of mine told me that I would be better off if I went to 14.5 x17 in a 4 blade and I think I may borrow his to try out. Frank
 
hey i want to thank you guys for the info on the prop
i went from a 13 1/4 x 19 to a 15 x17 and just like you said no more cavitation and more speed it throse you back when you throttle up
A BIG THANKS FOR YOUR HELP
you saved me alot of cash
thanks again
now all i gotta do is fix the knocking in reverse
go to repair section
 
step...glad to hear it worked out for ya!! ;) ...you ZOOMIN' NOW!!! ;D ;D

SFprovyn...gonna be hard to tell if right prop w/ out tach... ;)...
 
You are right. I just put in an old Merc tach and hooked it up and saturday my friend is going to loan me a 15.5 x 17 3 blade aluminum prop that he has on his v-20 center console also with a merc 150..He gets around 42 and has bottom paint also. He thinks I should get 4 MPH more with the bigger prop. I'll let you know. Thanks Frank
 
the right prop?

i have a 5.0 mercruiser I/O and my top speed is 35 at 4200 rpms I have noticed a lot of cavitation. Anyone have a good idea about what kind of prop i should have The prop on it now is a 19 pitch. not sure what diameter but there is a little more that in inch clearance with the trim tab. Maybe a four blade thats bigger?
 
you guys keep mentioning bottom paint. does it make much difference if you have it or not? better speed?
 
bottom paint

Bottom paint creates more drag and you lose speed. You dont lose much though, about 1/2 a knot maybe 1 knot. You only need bottom paint if your going to leave it in the water. If its already on there dont take it off. Its way to much work.
 
You must log in or register to reply here.
Back
Top