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Smart Tabs SX, anyone know if they work on Jetboats ??

Marky Mark

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Hi, Just joined the site from the UK. I used to have an Exciter 270, which I loved dearly, but was too shallow a 'V' on the hull for the sea which I use my boats on the most.
I now have a very old Bluebird Jetstar 520 ( it's a 1976 vintage ). It have a Castoldi jet drive with a 3.4 litre Ford Essex V6 engine producing about 185 HP.
My problem is that when trying to get up on plane with a skier or wakeboarder, or even a load of passengers, it doesn't want to pop out of the hole & get up on plane.
It has plenty of power & does 48 mph without passengers, but it's quite heavy & sits pretty low in the water when at standstill.
My question is I've seen 'Smart Tabs SX' at a local supplier. They can't help when I questioned them about fitting them to a Jetboat hull. Has anyone fitted these to a Jetboat ? If so do they work as well as they say on Youtube !!
 

Cobra Jet Steering LLC

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I believe glassman put trim tabs on his Yamaha jet boat and it helped , I would also suggest you get the impeller re pitched to provide a better hole shot . someone probably pitched it for top speed but this would reduce the low end torque and result in sluggish hole shots as you describe.
If on the other hand it cavitates out of the hole then you have another issue.
 

Marky Mark

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I believe glassman put trim tabs on his Yamaha jet boat and it helped , I would also suggest you get the impeller re pitched to provide a better hole shot . someone probably pitched it for top speed but this would reduce the low end torque and result in sluggish hole shots as you describe.
If on the other hand it cavitates out of the hole then you have another issue.

I'd love to change the impeller, BUT no one makes them, only Castoldi.
The standard one is made from 'Nylotron' which is a name I think they made up, but basically it's nylon. To change the gearing so to speak, you change gears inside the gearbox so as to increase / decrease the speed of the impeller. These gears come in pairs & are approx £1500 + tax a pair. They do a stainless steel impeller for uprated engines which is a mere $1850 + tax, but it's still the same old pitch. Everything has to come from Italy which is a delay & expensive, but the quality is pretty good.
I'll try the flaps out & see what they do ???
 

Bruce

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I believe that the Smart Tabs are always down and attached to some sort of hydraulic strut.

Whatever correction they provided woild always be active. I believe that adjustable tabs would be better for you.

I am using LectroTabs https://jetboaters.net/threads/lectrotab-trim-tabs.71/

I mocked them up using cardboard cutouts then the manufacturer made them custom for a reasonable cost.

I can have no trim at all, a little bit to soften the waves or so much that it slows the boat down when I want to plow through a wake.
 

dan144k

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Marky Mark

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thanks guys, I've found a whole second hand drive unit, it's got a Stainless Steel impeller & a different gear set. I don't know if they are the right set of gears, I'm hoping that I can work out the reduction ratio! The drive unit was coupled to a Diesel engine, so might be about right ???
I'm getting to love the boat though, Took it for a long ride from outer London all the way up to London bridge ( 7 hours each way, mostly speed restrictions) without a hiccup! It's nowhere near as quick as the old Yamaha Exciter I had, but it does cut through the waves better & it's a lot quieter.
Thanks for your help so far, Jet boats just aren't as appreciated over here, nice to have a bit of experienced help.
 

Bruce

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@Marky Mark, next time you tour London could you take and share some pictures of The Golden Hind? My kids would love to see her. Thanks
 
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