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Thread: Prop" trim"

  1. #1

    Prop" trim"

    As you can tell I very new at airboats, sorry.
    I do boat a lot , I have a Hewescraft jet that I use the heck out of.
    Anyway, I'm still designing , I my mind, my water bug mini.
    I have a fairly firm Plan on the drive, snowmobile Clutch belt drive to chain reduction to a car front wheel spindle and hub ,driven by the chain, two blade wooden prop. Size yet to be determined.
    NEXT.
    Would there be a advantage to be able to trim the drive and prop on the fly?
    If I make the whole package pivot up and down with a seizer jack I could make the front lighter or drive it down harder or adjust for the load.
    On snow and gravel and ice I would think you would want a lighter bow.
    What kind of movement are we talking? Inches, fraction of Inches?, Many inches?
    You could use the trim to help clime over bumps maybe.

  2. #2
    Administrator Papee's Avatar
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    Re: Prop" trim"

    I have my front mount made of thread rod. I can adjust it in a couple minutes if needed. I did this when I was experimenting with the angle so I could adjust and test right on the river. After I found the sweet spot I never changed it again.
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  3. #3

    Re: Prop" trim"

    How much we talking for movement ?

  4. #4
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    Re: Prop" trim"

    Hey there. I was going through the actual trimming on my rig last spring and with Papee's help I got a mysterious hull lean tuned out. When you are looking for an adjustment measurement it is real hard to say " a 1/2" will do it". It's really an angle measurement you want between the propshaft's centerline (longitudinally) and the bottom of your hull. You can't just say 1/2' here or 1/4" there because the positions of the adjustments and the distance from the prop shaft centerline are different on each of our set ups. To give numbers to it though, I started with my porpshaft level to the bottom of the hull and add shim at the front of my rigging. My rigging is about 6 feet long and the prop shaft is about 64" above the bottom of the boat. I added 1/2" in total to the front of my rigging. I think Papee and I had a fairly in depth conversation about it over a couple of days on the forum here. Try looking our thread up. To summarize though, I'm in agreement with the bossman after my trials. set it for running free and don't touch it after.

  5. #5

    Re: Prop" trim"

    But you guys run Mostly on water right?
    I plan on running on a lot of snow ice and gravel.

    I cant help but believe there would be a difference.
    I'm really not trying to be a "BUT" Just thinking out loud

    On my jet the motor will not "Trim" .
    When the boat is loaded heavy It would be nice to have a trim to help get it on plain in shallow water.
    And on very Flat water It tends to Propose. a slight bow presser would stop it.
    I can use ,and do , power trim plates but they add some drag.
    Just saying.
    Last edited by Coyotes-R-Us; 02-05-2016 at 04:02 PM.

  6. #6
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    Re: Prop" trim"

    I found the thread. try searching for "engine tilt" if the link doesn't work.

    http://miniairboatassoc.com/forum/sh...48-Engine-tilt

    I'm from Central Alberta Canada. I run alot of sketchy conditions. Look for my youtube channel "drpeck76" for a couple videos if you have time. I find the more water you can keep under it the easier it is on parts in general. It takes big horsepower to run dry but I'm sure you'll build it to you what you need.

  7. #7

    Re: Prop" trim"

    Cool thanks


  8. #8
    Administrator Papee's Avatar
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    Re: Prop" trim"

    When you get a boat running free it is going to be your best adjustment for any running. When a hull is running free it is neither pushing down on the bow or transom. If your engine angle is pushing down on either end it will slow it down on the hill. If you have the hull running free but has a touch of porpoising sometimes just moving weight around will stop it. It's best to get your weight spread out first before trying engine angle. The more even it floats the easier it is to get riding the best it's capable.
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