cavitation on Super v pro with 200 merc...help

[Johnny Utah]

I have a 21 foot super v pro with a 200 merc xl tiller. I also have the jet that I periodically put on. Many times as I accelerate the prop spins out and I have no power. I am pretty sure it is sucking air.

Any Suggestions?

I though of trying to get an XXL lower unit because the cavitation plate seems to be higher than the bottom of the boat. It seems that Alumaweld would put a motor on that fits the boat but I don't know what else to do. I could sure use some advice.:passout:

If I need an XXL lower unit, any suggestions where to get one?

[Hawaiian Time]

I have a 23 Super Vee, 200 Offshore Merc that I converted to prop. They put a 6 inch extention kit on it so I could get low enough. Do you have an extention kit on it? If not, that's what you need or one of those hydralic lift kits to lower and raise the moter level. HT

[Johnny Utah]

Thanks HT. I already do have the extension. I will have to measure it to see if it is 6 inches. I think it is. Someone told me that means it is an xl shaft. The same person told me that maybe I need an xxl shaft instead. I am wondering if I need to buy a different lower unit.

[Hawaiian Time]

If Stevens installed it, I would go back to them. They did the install on my Super Vee and I don't have any problem cavitating other than on quick power turns of 360 degrees. I have a Pro series Vee which has the higher transom due to the rear full length cabinets. HT

[Boat Doc']

With the boat being properly set up for a jet when you install a lower unit the cavitation plate is 1 1/2 to 2 inches high which will make it break loose on hard acceleration and tight turns. If it performs unacceptably options are, stainless prop, jack plate, lower motor or cut transom- which means when reinstalling the jet you have to raise it back up. We recommend when running a prop/jet combo that you run a stainless prop which will eliminate most of the cavitation

[BUANA]

Get a four blade 19" stainless and you will not believe the diffrence

[Starfish]

Get a four blade 19" stainless and you will not believe the diffrence

I agree. Stainless can make a big difference, and you can even gain a bit more grip by having it modified to add extra cupping.

[Johnny Utah]

Thanks a million. You guys rock. The guy I bought it from had a stainless on it when I took it for a test run. It definitely felt better on the test run. Doc is right. Cavitation plate is 1.5 to 2 inches above the bottom of the boat.

I believe you guys but dont really understand why stainless makes such a difference.

Thanks

Fred

[OB1]

No flex with Stainless.
Think of it as if you were in mud with street tires verses the knarliest nobby tires made! Better traction! :twocents:

[Hunt'nFish]

Huh....so you guys say that he only need go w/ a stainless prop huh?
Interesting....considering I have a small pumped sled and was thinking of slipping a lower unit on, but am too cheap to flip for the jack plate.
Interesting.
Hunt'nFish

[Flatfish]

It depends on your transom height and how long the lower unit is.

[Johnny Utah]

Is there much difference in cost between a stainless prop and a jackplate? If not I may be inclined to get a jack plate.

[Hawaiian Time]

My Mirage 19 pitch prop for my 200 offshore Merc was $500 3 years ago. Don't know what the jackplate goes for. HT

[Starfish]

Retail price for a quality stainless prop can be $675 or more. However I generally get them for $250-$350 on ebay. YMMV.

[Flatfish]

There was a manual jack plate at craigs in portland yesterday for 160 bucks. This should fix the problem.

[Johnny Utah]

flatfish, could you send me that link?. I couldn't find it on craigslist.

[BUANA]

I believe that with the jack plate you will have issues when you want to run your jet.Your motor is going to be 4-5 inches farther back from the bottom of the boat which will cause water to hit the front of the jet foot and will cause drag and spray.The bay kit with the stainless prop is the best solution.I set up a boat ounce with a jack plate for prop and pump and it was a pain in the a$$.

[Flatfish]

Buana,

With the jet, you will need to bolt on a small piece of aluminum to extend the flat spot on the hull. Mine has 2 bolts. This takes about 2 minutes.

NR did this on many of their boats without a jack plate.

It seems it feeds the jet a bit cleaner.

[steelheaderz]

I have a 21 foot super v pro with a 200 merc xl tiller. I also have the jet that I periodically put on. Many times as I accelerate the prop spins out and I have no power. I am pretty sure it is sucking air.

Any Suggestions?

I though of trying to get an XXL lower unit because the cavitation plate seems to be higher than the bottom of the boat. It seems that Alumaweld would put a motor on that fits the boat but I don't know what else to do. I could sure use some advice.:passout:

If I need an XXL lower unit, any suggestions where to get one?


you could always change the pitch of your prop, lower transom, cut and reweld with stiffener for added support, or what i would recomend if you already have a bay kit is getting a cmc jackplate which i believe gives you an option of raising and lowering motor 6-8" up or down this would be the simplest way of solving your dilema call Motion Marine 503-557-1802 and see if they can make any reccomendations

[Finscent]

The answer is pretty simple. The motor is not mounted at the correct height. Whenever I had to do a conversion from jet to prop or prop to jet, the motor height on the transom always changed. pm

[Northwest Pest]

Power Hydraulic on mine from bobs machine shop and it works fine. Run the boat and find optimum spots for jet and prop running and mark them on your jack plate for future reference when you switch from pump to prop.