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Thread: My Surface Drive Rock Guard:

  1. #1
    Member mainer_in_ak's Avatar
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    Default My Surface Drive Rock Guard:

    After four attempts with my motor, I've finally learned how to eliminate cavitation or any change in speeds using a rock guard. The complete recipe took some design changes, until perfection was achieved. So far, I've finalized my template rock guards for the 6.5, the 12, and hopefully Sunday, the 18 will finally be covered. My rock guard is built from 1 inch thick UHMW that is grooved to fit over the skeg. The fit is so tight, that a rubber mallet is needed to get it on. 5 counter sunk screws with nylock nuts, and she's a done deal.


    I don't like using metal as a rock guard because every time you hit a rock, all that force (metal to rock) is transferred to your frame. The UHMW provides a vibration deadening absorber that eases the harsh impacts that would've normally gone to the frame.


    The rock guard provides an additional 1.5 inches of protection just below the skeg. This will also eliminate abrasion to the skeg. The guard terminates just shy of the furthest most tip of the blade. A deep 45 degree routered edge helps the guard slice through the water without cavitation or change of speed. Thanks Boudarc and KKalaska for showing up and helping with video and pictures. Here's a customer's armored motor tested on my Esquif Cargo(first rock guard for the 6.5):

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    Member mainer_in_ak's Avatar
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    With Boudarc, KKalaska, my son and I, we hit 10 mph. At this point, the boat began to oil can. The weight was 780 lbs. Same thing with the boat loaded with two guys........12 mph with serious oil canning. So.....we hit the limit of the boat, would've probably done better with a stiffened hull like what Piper n Lowrider did the their Cargos.

    I'll report back on the 18 horse Copperhead, as Sunday is the day to fabricate for that particular model.

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    Thumbs up Very nice work there sir

    That's really nice work there Mainer. +1. And what a beautiful day to be out testing on the water.

    That'll teach me not to play accountant when I could be out testing. I would have loved to see that motor operate on my Albany; no oil canning in my craft; Scott build's'em strong.

    Rain check?

    Digression:
    Oh yeah. While you were making breakthru's in the boating world, I did discover an extremely cool new (free) product that would help any small business graduate from "shoe-box accounting" methods. I've now discarded the home built software I've used the past dozen years or more, and will use this new product from now on for all 3 of my operations here. I'll shoot that over to you to see if you want to use it do facilitate the accounting for your small business there.

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    Great idea Mainer! You ouhta sell those too if the manufacturer isn't. Camo that motor and it would look great on my cargo.

    My fix on the oil canning has worked really well..with 300 lbs in the front and the 9.9 Merc it just skims along. It does skid some in hard turns but then I tend to "hotrod" more than I should. I haven't run the GPS to get speed but I know it is faster than the oil canning hull for sure.
    Somewhere along the way I have lost the ability to act politically correct. If you should find it, please feel free to keep it.

  5. #5
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    that guard looks great on the SD it will work great
    SID

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    That looks like it will save alot of filing on the prop...
    Good addition to the mud motors.

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    Member tboehm's Avatar
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    looks like you have things working nicely and having fun to boot
    Semper Fi and God Bless

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    Quote Originally Posted by budman5 View Post
    That looks like it will save alot of filing on the prop...
    Especially important both because that's a high dollar prop (how much Mainer?) and because since his rig is designed for shallow water rock gardens, he's going to hit the rocks more than most people would.

  9. #9
    Member mainer_in_ak's Avatar
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    here's the 12-18 hp model after one season of dipnetting salmon, hauling camp, caribou and moose meat up shallow stuff:

    gave them all the name of "rapids runner" rock guard. At the rate of wear I put on one, it may be impossible to wear down the guard in anything less than 4 years or more. Darn irons in the fire.......more than I bargained for.


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    Michael

    Thanks for the guard. I am looking forward to the money it will save on prop jobs.

    I will do a review on it and post by Aug.
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    Member mainer_in_ak's Avatar
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    Quote Originally Posted by Duckhunter01 View Post
    Michael

    Thanks for the guard. I am looking forward to the money it will save on prop jobs.

    I will do a review on it and post by Aug.
    hey thanks, make sure to stop by my big man-cave shop. great place to loiter.

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    Member Laker Taker's Avatar
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    Quote Originally Posted by mainer_in_ak View Post
    hey thanks, make sure to stop by my big man-cave shop. great place to loiter.
    Hi Mainer..Is this an open invite?? I just realized that we're practically neighbors! (I even used a contraction for you this time)

  13. #13
    Member mainer_in_ak's Avatar
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    Quote Originally Posted by Laker Taker View Post
    Hi Mainer..Is this an open invite?? I just realized that we're practically neighbors! (I even used a contraction for you this time)
    pm'd yah, I'm always avail for a face-to-face.

  14. #14
    Member Laker Taker's Avatar
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    Quote Originally Posted by mainer_in_ak View Post
    pm'd yah, I'm always avail for a face-to-face.
    PM"d ya back, let me know whatcha think.

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