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Porposing

crabby

Well-known member
Has anyone put L brackets on each side of their hull instead of a trim tab and if so does the bottom of the bracket have to sit right at the waterline I have seen them on some hulls and have heard that they do work any help would be appreciated
 
On my fiberglass hull I installed 2" x 6" long aluminum angle on either side, mine are about 1/4" above the bottom of the boat so when I run ground they don't dig in to bad. Put a straight edge on the hull bottom to set them up. The aluminum allows me to make adjustments in the field, plus they give if I hit anything. They do help some, and with proper load distribution porpoising is almost done away with. I like them since they have a smaller profile than a trim tab, had one before and in my opinion the tabs work just as well and are more convenient.
 
So you didn't mark the water line on the hull when it was in the water just mounted them 1/4 of an inch from the bottom of the hull
 
I put two of them on my hull also 2x9" or so. My hull has a little bit of a bow to it so they don't touch the ground if I am on a sand ber or something. I have mine about 1/4" up from bottom also. They cured my porposing right off the bat, but I have since relocated my fuel tank about 29" farther forward from its original location and I haven't bent them up out of the way yet to see if i need them at all anymore, but to answer your question yes they do work well.
 
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here's mine. each tab has an effective surface of 1" x 9". we may conclude here that majority would be 1/4" or a quarter inch off the bottom like mine too.
 
let me just add; that 1" tab width may not look much to be effective but be aware that it can already cure the porpoise and may even make your rig ride on the nose! my boat's porpoise went away but when i hit 30+mph, somehow it gets to ride on the nose. i was aiming to cut 1/8 inch off the tab but i have not yet done it maybe soon. got to finish a new boat.
 
I put one of these on a cottonmouth that used to have a slight porpoise problem and it did help. However, the boat that I have now will porpoise like crazy on smooth, deep water and the only thing that stopped it was an electric trim tab.
 
Worked for me. My old boat had been re-built so many times by the time I got it there was little hope of ever making it properly balanced. I'm convinced the proper tweaking of the motor angle and load balance. But thanks to the previous owner of our boat - a complete re-rig would be necessary to get the right motor angle and balance. You can only "patch" stuff so much.

So the little angle trim tabs worked for me. Still have a porpoise, but the tabs pushed it up to not happening till a much higher speed. So the boat is fun again.

I've got a 1 inch tab on each side of the transom - about 5 or 6 inches wide.

I mounted mine FLUSH with he bottom of the hull by setting the hull on boards, and using them as a guide to set them flush.

Our boat don't run dry, but we'll still bump it up on land to park it and I mounted the tabs out near the outside of the hull where it starts to angle up a bit so when we go on land, those tabs are off the ground and don't get all bent up.

Like I said - Not pretty but it works. :)

matt.
 
matt

for me, powerful or not, big or small, dry or wet runner... all airboats are made equal and all are made out of art and beauty!

so, no matter what you have there, it is an airboat to me :wink:
 
leo_081103":n31y6avj said:
matt

for me, powerful or not, big or small, dry or wet runner... all airboats are made equal and all are made out of art and beauty!

so, no matter what you have there, it is an airboat to me :wink:

I agree, Leo. I've been around airboats for many years and I never get tired of looking at them. Each and every one of them are a work of art. You never see two airboats just alike. I still get the same thrill out of watching them run today as I did when I was a kid. It just never grows old for me.
 
Well, after I had someone tell me my boat was not an airboat if it could not run dry - I like hearing what you guys are saying. I feel the same way. :)

It's looking like my next boat is gonna be a 9 or 10 footer with a 2 cyl ultra-light airplane motor. ;) ;) :D
(That's another boat that they tried to say was not an airboat! But those little suckers DO run dry!)
 
it's an airboat Matt, no one can take that away from you. say what they want, it only adds to the fact that they dont really know what Airboating is. i must say, it's not what the limitatations nor the figure of how an airboat is:

"it is the thump of my heart and my awe whenever i see an airboat and most of all whenever i ride my airboat" :wink:

let me guess, hmmmm............. rotax 582 65 hp 3 blade 72" warp drive on a 10 footer = HOT!!!

or a hirth, hks maybe,..... just build it man and we will come.... to see it.

btw, i once had a 100 hp rotax 912ULS airboat. imagine, 100 horses out of a 140 lbs installed engine.
 
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