New Boat / Terrible Hole Shot

[Flex]

I have a 13 3/4x 17 and a 14x17 pitch I would sell cheap if interested OP.

Also have a 13 3/8x 15 prop.

[nitro_rat]

Ditch the tired 90 and buy a strong 140 to hang on it! If you worried about overpowering the hull, just throw your 90 hp hood on it!

[stick]

Ditch the tired 90 and buy a strong 140 to hang on it! If you worried about overpowering the hull, just throw your 90 hp hood on it!

I've been keeping my eyes and ears open locally for a good 140hp.

[stick]

ok lets start again
you have a worn out engine on a heavy arse end boat and have taken off the foil that helps get heavy rear end boats on the plane.
you also have a crap prop that will not bite like a stainless prop and wonder why it is not jumping up on the plane.

now first of all a vent in a prop is not a band -aid by a long way, its a way to get a prop to be a two-stage prop that even most big powerful motors have on them.
The foil will help a lot to lift the back end of the boat out of the water and only needs to be touching water until boat planes off, then it should be above water.


Unless you re-power or re-build the motor you need to
1 / sharpen the prop like a razor, ( you need all the help you can get )
2/ vent the prop or buy a smaller pitch (lose top end) ..venting the prop , even an alloy prop will give better holeshot, then act like conventional prop once on the plane.
venting just helps the motor get up into its powerband faster.
3/ fit the foil back on.
4/ make sure once on plane the foil is not hitting the surface of the water, if it is then raise motor bracket to get foil 1 inch above water on plane.
5/ keep as much weight as possible away from the back of boat
6/ give it a go with powertune to try and make compression come back and rings free for more power all round.

on top of all this make sure the carbs are sunced to each other, fresh fuel correct spark plugs with jump gap capable of atleast 7/16ths
check timing to make sure that is correct too.
any dings in the prop need to be filed or cleaned up, also check prop for run out and that all 3 blades are pretty much the same.


on the cheap you can get a 13 x 15 omc alloy or 13x 17 omc alloy, very different props to the old Michigan crap, and much better for your needs
if going stainless I would put a 13 x 19 Omc sst on it , vent it and hang on. again a cheap prop to buy seconhand on fleabay etc.

No need to start again, you're misinterpreting what I'm asking. I am asking how to vent a prop, not a magic bullet for a tired boat/motor. We covered that mostly on the first page.
I have no intention of rebuilding this motor or throwing money at it is all I'm saying. I'm fairly satisfied with how it runs, but a smidge better outta the hole would make me happier. If I screw up drilling the holes, I'll toss the crap Michigan Wheel and get another prop. If nothing works, I'll deal with it until a find a stronger motor.

[phillnjack]

ok to vent the prop is dead easy .

on the prop hub at the bottom there is a step, do not count from there count up from the outer hub measure up about 15mm and centre punch .
you need the centre punch to be about an inch away from the blade itself and just drill a 1/8th hole, then go up in sizes to around 12 mm.
if you have a bench drill it is a real easy job as can just put a long bolt through the prop to hold it in place. put a piece of wood between prop and table to stop the prop
and also help keep the table from having a mark on it.

before you drill the holes look inside the prop roughly where the holes will be to make sure there is NOT a rib that you might hit. if there is move more away from the blade.

Drill the holes straight DO NOT angle them, it dont work so good (I have tried that and it slips too much before proper bite).

I have had great success with alloy props and stainless props when venting, its also good for trolling as you can actually go a touch slower than the norm
without fouling the plugs for longer periods.

I have had some allo y props with the ribs interfering and had to drill half way across almost, and they still work good.

here is a few pics of some ive done. the little black alloy mercury prop was too much pitch and my boat struggled big time getting on the plane with just me.
once vented with 2 if us its jumped onto the plane and was great little prop.
the other 2 props I have right now and altering them for different uses,

hope this helps