trim tabs in the way, model I mercruiser

hi folks, got the boat listed below. tihis is the first time i've wanted to change a prop from what i already have. i have a 21 pitch "fan blade looking" prop. i think i have issues when trying to get wot. i can get it, but seems like i have to trim to high to me. when trimmed down where i think i ought to be i get maybe 3900, and can go lower for a wot run if i trim down more(38-37). can get 4100-4200 trimed up high. anyways, i found me a 19 pitch at the dealer, alum also, dealer says it's a mercrusier prop. thought i'd just R&R it. wrong. the 19 hits the trim tab. back to the dealer and now have a thinner thrust washer. cool, not. still hits the trim tab. i'd put my 21 back on but i musta found me something solid on the river yesterday and lost me a tip of a blade. enough that i think i don't want to run it for bein outa balance. so...... i had a 17 alum. around and put that on. thin thrust washer and it does fit. but man, is it close to the trim tab. end play on the propshaft is round abouts 1/32"- 1/16".
question is i guess. are there special props designed to be used with that mighty long model I trim tab? i was gonna R&R that too, but bet i will be meltin that off if that's what i want as i have started to strip the drive on the trim tab bolt...any one have any ideas?

Re: trim tabs in the way, model I mercruiser

it is your diameter that hits the trim tab

what dia are they

Re: trim tabs in the way, model I mercruiser

See if you can buy a smaller trim tab or cut your current one down.

My Alpha doesn't have one at all...

Bob

Re: trim tabs in the way, model I mercruiser

i'm per near sure i could use the shorter tab. had that on my trisonic w/ model I drive. but this is what i believe to be the proper tab for my model I. this is the 17 mounted ontoit. man it is close. bummer i just measured it. .014"
don't know if i could use the no tab at all idea. i think this is old technology i got here and is probably gonna need some kinda trim tab to keep me from haveing the steering pull.
heres what i got.




i'm not sure on the dia. issue from my 21 to this 17 or the 19. reckon i should check that out. guess i was assumin the 21 was lager dia.

Re: trim tabs in the way, model I mercruiser

interesting, no one thought of this. seems to me like a boat is about 1/2 fix to taste and 1/2 fix to spec. anyways. this was a fix to taste answer. talked with my dealer and he says .014" aint enough whatever pitch. plaine and simple answer. make it fit. hum. seems like a good idea to me. put me the 19 back on and grind the trim tab to fit. dealer thought 1/4"- 1/2" clearance for the flex of aluminuim. cut it to 3/8"-1/2" dependin on the blade. worked mighty darn good for a first attempt. gonna have to give him his bread for the prop i guess. $125 i think, used with a few minor scratches in it. on the black paint.. he loaned it to me. mighty of him. and sold him a prop too. everyone wins.
pacein my buddy in his baylineer on a gps i'm gettin boughts 42-43 mph. a richious hole shot and cruise at 22-2300. wot 4200 trimed about right..... i think.....

Re: trim tabs in the way, model I mercruiser

oh, and i can still let go of the wheel when i'm on plane. drives stright by itself. amazin. for no power steering..... soon to be next problem, slop in the rack and pinion steering. i hope.........i think.

Re: trim tabs in the way, model I mercruiser

That trim tab is actually a sacrificial anode. Mercruiser makes different anodes for different prop applications. You can buy a replacement anode to fit your prop instead of grinding it down. I put a SS prop on my boat and I replaced my anode with a flat anode that has no fin. I could tell no difference in handling as far as having any trim problems. The SS prop made my boat handle far better than the alum prop ever did. There are four different anods I think. Three with different trim fins and the one without.

Instead of grinding it you can look the part with the right part...besides, it is dangerouse to grind on those things.

Wes