Greg Shoemaker or other Jet Guru's

[rivercrazy]

I have a 98 Shockwave 21LS. Its very similar to many other mini day cruisers out there and looks just like the old Eliminator Sport Cruiser. It has an 18 degree bottom, 4 full length lifting strakes, reverse chine, and a rounded keel. It has a Marine Power 454mag with a non set back AT-309 pump (it does have the deep mounting housing) with an A impeller. It also has a FTN Place diverter (3.125" nozzle) and their large rudder. It runs great and is strong out of the hole.
When turning hard at low speeds the pump will blow out if you give it WOT. I think this is due to the hull leaning and the pump sucking air. I installed a loader grate (two outside metal angle irons directing water flow to the upper part of the impeller) and this help quite a bit. However, it will still blow the pump out. Is this problem possibly caused by the turning fins on the intake? Is it a characteristic of an American Turbine pump as their intake is smaller than some other brands? Is there anything I can do to reduce or eliminate this problem? I heard DPS Inducer might help but is a little pricy. Any ideas???

[spectras only]

Rivercrazy, my 20.10 spectra is practically the same size as your boat,except it has a 12 degree deadrise which allows the boat to slide slip at hard turns,rather than lean on the side,keeping the intake loaded.The 19 spectra we run with the same type Berkeley intake will blow out at hard turns because it has a sharper V ,and it leans on turns.It's a lot faster than the 20,but I like the handling better of the 20 footer.Both boats have the fins on the intake.
[This message has been edited by spectras only (edited January 18, 2002).]

[rivercrazy]

Thanks for you input Spectra. My boat does not slide or skip no matter how hard I turn. Its as if its on rails. I guess the 4 lifting strakes, intake fins, and large rudder makes it stick.

[got river?]

Rivercrazy,
I have the inducer, and experience no blow out at all. Before the installation of the inducer, I had slight blowout. My boat is much smaller and probably lighter than yours, (19'), so the inducer may not help as much on your hull as it did on mine. Most of the improvement I have noticed with the inducer is the hole shot.
[This message has been edited by got river? (edited January 18, 2002).]

[rivercrazy]

GR. What size impeller are you running?

[racingrascal]

Don't turn so hard.

[RiverDave2]

I'd grind off the fins on either side of the pump intake as an experiment first. How much does one of those intake grates cost?
(keep in mind I dunno nothin about jets)
RD

[shockwaveharry]

Don't grind the fins. I was recently talking to a guy in Blythe that lives for this kind of stuff. He was telling me about the time he took the fins off his 19' Eliminator and the boat got so squirrelly it swapped ends at 50 MPH! This is second hand information so confirm it with someone who knows for sure.

[flattie]

I did a similar stunt like that with my buddies jet boat it scared the crap out of me expecially when you have half the lake coming over the deck and the waters pretty cold

[greg shoemaker]

Back in the old days when circle racing was the rage you would cut fins back on the fin you desired to make a hard turn on. T he fin would starve the intake for water thus cavatatition would occur. We try not to do this now because the boat will loose high speed tracking and become a handfull to control. You have to remember that all of these boats were always turning to the left so the inside or the left intake fin was modified. These boats also had keel fins so the turn could still be made. Take it a little easier in the turns and the problem will improve greatly. Greg