Trim Plates on jet boat ? Pros and Cons?

[kcsteck]

I have a 76 18 ft Tahiti and was wanderin would trim plates help my boat at all. Its a real heavy son of a gun compared to my buddies Bahner that just gets up and jumps out of the water when he nails it. My slug goes good but dont leave the hole like his. was just wanderin if the trim plates would help at all? or is that more for like a day cruiser.Let me know what ya all think.some guy sellin some that are 7 in by 21 inch for like 40 bucks with all hardware to install them . came off a 20ft Hawaiaan.
K-dog

[kcsteck]

no one has any input on this? come on guys!

[v-drive]

I have them on my 19 ft daycruiser and while it isn't fast at all I really like them. The boat really seems to get on plane quick. v-drive

[BrendellaJet]

Do you have a diverter on the boat? How much bow lift at take off? How much HP? If the boat weighs a lot you might need more power to compensate...

[kcsteck]

yes I have a diverter. not alot of bow lift, but some. 455 about 400+HP boat goes GPS 58 @ 5000 RPM then motor sucked a hardened seat out wasted the piston. tore motor down turns out heads were junk . had cracks in 6 out of the 8 runners lettin in water,crank was toast and had spun bearings and it was still runnin 58 and runnin hard. Motor shop cant believe the thing was even runnin! Needless to say rebuildin motor and was just toyin with idea what I can change while motor was in shop.I was thinkin trim plates to plane quicker ?

[BrendellaJet]

yes I have a diverter. not alot of bow lift, but some. 455 about 400+HP boat goes GPS 58 @ 5000 RPM then motor sucked a hardened seat out wasted the piston. tore motor down turns out heads were junk . had cracks in 6 out of the 8 runners lettin in water,crank was toast and had spun bearings and it was still runnin 58 and runnin hard. Motor shop cant believe the thing was even runnin! Needless to say rebuildin motor and was just toyin with idea what I can change while motor was in shop.I was thinkin trim plates to plane quicker ?
Well, Ill say it once-lose the olds and build a nice BBC. The parts are very available to do the swap. You will see the biggest improvement with this change not to mention vastly improved reliability.
Id make sure your pump is tight. You might be able to get rid of a little more bow rise with the tabs, but they aren't going to help you accelerate faster(not noticeably anyways). You need more power.

[jbone]

Stupid question, but how do you position your diverter for taking off?
I know some that start with it up and wonder why there is so much bow rise.
I start mine all the way down and raise it up as I get on plane. I keep slowly adjusting up til I hit the sweet spot.
My heavy (3400 lb) 21 has very little bow rise when I gun it. It is no rocket, but all movement is forward.
My guess is trim tabs are not necessary with a diverter.
J

[kcsteck]

Brendella. If I could... I would on the motor change. And I still might in the future. But thats alot of changin stuff and alot of cash$$$ Motor,engine plates,headers,starter,dist,intake.etc.etc$$$$$$$$ $$$ What I should have done was buy a boat with the chevy already in it. or sell the boat and get diff one with the Chevy.Otherwsie gonna loose my ass on the boat.it would cost at least 3k Id think to do the conversion.not gonna get that back.I did get 3 seasons out of the 455.im gonna try and patch it for now I guess usin the 455 for now. Maybe I can get lucky and someone would like to buy the 455?lol
Jbone: Yes I take off with the diverter down and raise as I go.I guess split bowl and droop would be better Idea I suppose.
Ill pass on the trim tabs then. I didnt want to really drill holes in back of my boat.
thanks for all your input Guys.
Casey

[ck7684]

Only time I take off with the diverter up is to watch the geyser :D otherwise I have it down and it planes out almost instantly with no bow rise. My boat is a bit lighter than yours so I would say you just need more power or maybe tighten up the pump...