Chine Walker UK

Formula 311 running 502's 8.71 blowers, 17" 29 4 blade props on ssm v drives.

Just bought in UK so it difficult gettin help from people used to dealing with 60HP out boards.

motors only uprated a month ago so still testing / running in.

It acelerates fast to 10 mph then just cavitates a lot doesn't move any faster, then you rev it to 5000 rpm for about 30-40 seconds untill it bites and shoots off to 35 mph.

Is it a prop problem ? the drives don't look low enough into the water when the boat is out the water the whole prop doesn;t look below the keel line. Does that sound right.?

Gary Anderson

Which way are the props spinning?

Cord

iTrader: (2)

Try dropping your tabs. You don't want to be cavitating your props like you are.

Chine Walker UK

clockwise?

should i try different props ? is a 29 pitch to extreme? or try to get the leg lower? can you get spacing kits for ssm drives? are they difficult to fit? should the whole prop be fully beneath the hull when drives are down and by how much?

i set off with tabs fully down then after it eventually starts to plane pick em up. What happens if i keep cavitating them?

Gary Anderson

Do the props top spin outward, or inward?
If inward, try swapping the drives. Outward will have more stern lift and get out of the hole better. You may lose a couple mph on the top end though.
The SSM V should have the prop shaft about even with the bottom of the boat. If it is too high for that hull, spacers are available. Try Dollar, they should have them in stock. Not sure if that will help a lot. A 4 blade prop will do better too.
Gary

Chine Walker UK

not sure if spin inward or outward will check it out come back to you.

the prop shafts are about in line with the bottom of the boat.

they are 4 blade too.

think i will get a co pilot to help adjust tabs and drives on the next test run to see if it will get out of the hole quicker.

if i changed props what do you recon to try?

Cord

iTrader: (2)

When you cavatate the props that bad, the blade of the prop will actually erode. You are also flexing the hell out of those blades. Now they are extra thick to with stand the forces of surfacing, but you're gonna break one eventually. Besides, if you ever get into rough water, you won't be able to plane off at all. Try trimming the drive in all the way with the tabs all the way down. Slowly advance the throttle until you feel the props start to slip. Now throttle back so they can rebite. Before you loose your forward momentum, push the throttles back forward. Also post a pic of your transom. I want to make sure you don't have anything disturbing the water flow to the props.

Lmarth

Chine Walker-- Just a few observations based on the fact that I've got a boat with a high 'x' dimension running SSMV's with 4 blade 17 1/2x29 labbed props. It is a little tricky getting on plane. If your boat is like mine, it sits a little lower in the water at the stern compared to the same hull without the weight of the blowers, trannys and Speed Masters,etc. The effect of this is that the stern can block the flow of water to the props. You'll find you need some Tab, but not too much, because with the high 'x' dimension you'll get the props too high if you tip the bow over too much. This was all explained to me a few years ago by one of the mechanics that now works on Extreme Exhibit who is familiar with my boat. For me, it's like starting out in a car in deep snow-- just keep feeding the gas and don't give it more until it's hooked up and not spinning. I usually need 5000-5200 rpm to get on plane. I've seen experienced boaters struggle getting my boat on plane. One, two and three inch spacers are available for the SSMV's. Based on what you said, I'd say your 'x' dimension is even higher than mine based on some of my pictures. My props turn outward. Good Luck!

Chart

You have pulled your anchor up all the way, and completly untied from the docks, right?

Audiofn

Take The Trailer Off The Boat When You Launch It!!!!! :d:d