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  1. #31
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    I litterally went through the exact same process with my current boat. I had a stock gearcase, with that same pickup. Bought it, discusted wth its poor design, had to cut and modify etc. I could jack the motor sky high and got sweet speeds doing so. I decided to change it up and got a bobs lwp. Removed the tranom p/u. And ran outta water about 1/2" lower on the jplate where I previously got my fastest speeds. So I have decided to put the transom p/u back on and gain another 4-5mph from jacking up my motor more. I messed around a lot with the transom p/u and found that if you mount the short edge flush with the bottom of the boat (like it is in your pic) and long edge under the boat, you actually get crappy pressure. I ended up getting the best pressure mounting it like the instructions said, the long edge flush with the bottom of the boat and short edge 1/2" above.Idk maybe it had something to do with air assist but thats were I got the best psi (around 6-7psi at 81mph)

  2. #32
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    Thanks. Its to find someone else actually used one of these!
    How did moving the pickup up and down effect speed? Its hard for me to get good consistent tpo end runs with my 80+ mph prop because the boat is SO sensitive to little changes.
    13' Biel tunnel AKA "Flight Risk"
    13" Modified Yamaha V4 - 101 mph

    21' Paramount
    Mercury 300 Promax

  3. #33
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    I finally went and got some hose so I could hook this thing up and found more issues with this Bobs pickup. For some reason, they used a compression fitting at the pickup end for attaching the hose. I bought some of the re-inforced high pressure hose since there could be quite a bit of pressure at high speeds. Well, the good hose will not fit in the compression fitting. Its too thick. There no reason for the compression fitting, should just be a barb fitting like it is at the lower unit end. So for $50, you get a poorly designed bracket with a square stainless tube (that was an inch longer than stated and had to be cut) welded to a cast iron 90 degree fitting painted silver to look like stainless with a fitting that cant be used with the proper hose for the application. Yup, that about sums it up. I am in the market for a foot throttle and it will NOT be a Bobs Machine product.
    13' Biel tunnel AKA "Flight Risk"
    13" Modified Yamaha V4 - 101 mph

    21' Paramount
    Mercury 300 Promax

  4. #34
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    ...yep. I had the same opinion of that fitting. Bobs should stick to lower units and motor mounts LMAO. Of course, I've seen a couple gearcases they sent that werent too great either... :/

  5. #35
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    Finally got a chance to do a test run today although the wind kept the speeds down. No problem with the pump priming. I actually watched it pull water through the tube up over the transom while I cranked the engine to start. Immediately had pressure. I had the front edge of the pickup about 1/4" above the running surface with the trailing edge of the pickup even. Lost pressure as soon as I got on plane. Had to drop it so the leading edge of the pickup is just a tiny bit higher than the running surface to prevent it from sucking air in from the sides. The angle on the pickup is pretty steep and I am sure I can start cutting that down to reduce drag.
    As far as performance, the boat loved it. I had 20 psi at about 70mph which is much more than I had before. I raised the engine a full 1/2" (jackplate is manual) and it actually felt like it got on plane better. Instead of going bow up and plowing up onto plane, it kind of shot forward with less bow rise. The wind was howling and I purposely left the GPS at home so I wasn't tempted to see where it ran but I ran across the bay in some snotty white capped water and it just ran flat and floated across it. Passed a guy in i/o sport boat that had a very confused look on his face! Wish I had a video camera today because you would be amazed at how this little boat was eating up the white capped chop at 50mph.
    Boat definitely likes the extra transom lift of running on the bottom of the bullet. Boat felt liked it accelerated better and porpoised less through the tunnel hull transition zone. My gut feeling is that my 28 cleaver is going to be too small as I spun it up to 6400rpm real quick. I have a 30 cleaver to try but now that I know this works I can start playing with the setup. I also need to clean up the install with some nicer rigging. This was just for testing.
    The only downside is the engine is getting so high that I am a little concerned about stability when turning. I eventually would like to cut the midsection down but until our business picks up that isn't happening. Right now it looks like I have R2D2 on he back of the boat!
    Took some quick bad pics:
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    13' Biel tunnel AKA "Flight Risk"
    13" Modified Yamaha V4 - 101 mph

    21' Paramount
    Mercury 300 Promax

  6. #36
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    Edgewater,B.C. CANADA
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    Looks like your body work on the gearcase is holding up?

    Dave

  7. #37
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    Its holding up ok. I may have done some damage today though. I plugged off the fitting at the top of the Bobs LWP when I hooked up the transom mounted pickup but I didnt plug the intakes in the front of the nosecone. After I ran it today, I noticed a big blister on the side of the gearcase along the seam where the nosecone is epoxied to the gearcase. My guess is that with the fitting at the top capped off and water being forced into the intakes it created enough pressure to blow out the epoxy. Wouldnt be an issue if it was completely welded around the perimiter. I will probably just remove the Bobs nosecone and weld on a TH-Marine nosecone (no LWP, just a nosecone)
    http://www.thmarine.com/product.cfm?PRID=37
    13' Biel tunnel AKA "Flight Risk"
    13" Modified Yamaha V4 - 101 mph

    21' Paramount
    Mercury 300 Promax

  8. #38
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    A few years ago Bass&Walleye mag tested 5 or 6 different nosecones the Bobs cone was the fastest best handling. Sure would suck if you lost speed and stability by going to a different cone. May want to plug the holes on yours and refix, may even gain some speed with the holes plugged. Just something to think about.

    Dave

  9. #39
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    Maybe...its not really in the water anyway. I should probably first try just running without. Cant blow out since its not in the water but I think the extra length gives some added transom lift. Thats about 70mph in my sig pic and you can see the point is out. Thats also 1/2" lower than it is right now.
    13' Biel tunnel AKA "Flight Risk"
    13" Modified Yamaha V4 - 101 mph

    21' Paramount
    Mercury 300 Promax

  10. #40
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    Played with the height today and had a steady 20psi with only 3/16 of the pickup tube below the running surface at 70mph. Pretty wild seeing the needle just sit at 20psi no matter how fast I am going. Going to take another 16th off and smooth the transition into the pickup with a little marinetex.
    13' Biel tunnel AKA "Flight Risk"
    13" Modified Yamaha V4 - 101 mph

    21' Paramount
    Mercury 300 Promax

  11. #41
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    Twin Lake, Michigan
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    I'm not sure about the mounts either. The ones I bought looked like a failed high school shop project. I was so dis-satisfied with them I threw 'em out and made my own.

    These are precision made parts, they look right and they fit right. Then I made more, now everyone with a Mercury can have this quality for less $$$. The rest is history.



    Quote Originally Posted by thomast87 View Post
    ...yep. I had the same opinion of that fitting. Bobs should stick to lower units and motor mounts LMAO. Of course, I've seen a couple gearcases they sent that werent too great either... :/
    Last edited by Bruster; 12-12-2010 at 07:08 AM.
    Bruster's Mercury solid motor mounts, details here:
    http://www.powercatboat.com/Bruster/Bruster.html
    I'm been living in fast forward, now I need to rewind real slow....

  12. #42
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    Did some final shaping on the pickup today. Thought I would share sme pics if anyone decides to try the same project. The overall pickup area exposed is 3/16" x 7/8" which is more intake area than I had with the three 1/4" holes I was using in the Bobs nosecone.
    Since I was grinding I went ahead and tapered in the sides making it a little more narrow with no blunt edges. I used the white plastic in the pics to represent the hull.
    I need to get some nicer hose and fittings. I was looking at silicone heater hose which has a good pressure rating. looks good, and bends nice. Any other suggestions on hose? Braided would look nice but doesnt stay nice in salt.
    Now if the wind will stop blowing I will put the big prop on and get some numbers.
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    13' Biel tunnel AKA "Flight Risk"
    13" Modified Yamaha V4 - 101 mph

    21' Paramount
    Mercury 300 Promax

  13. #43
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    I wonder if it would be at all possible to use this setup on a v-hull?

  14. #44
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    Quote Originally Posted by wanagofass View Post
    I wonder if it would be at all possible to use this setup on a v-hull?

    I dont see why not. A V hull doesnt have nice clean undisturbed water in front of the prop so you dont gain from the running the engine at the extreme heights as a tunnel though. Not sure you would gain any performance.
    13' Biel tunnel AKA "Flight Risk"
    13" Modified Yamaha V4 - 101 mph

    21' Paramount
    Mercury 300 Promax

  15. #45
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    Quote Originally Posted by Mr. Demeanor View Post
    I dont see why not. A V hull doesnt have nice clean undisturbed water in front of the prop so you dont gain from the running the engine at the extreme heights as a tunnel though. Not sure you would gain any performance.
    I think you would if you had a stock gear case though because you can only go so high before the l/u intake holes are sucking air. In a case like that, would you plug all the stock intake holes if you were running one of these transum-mounted water pick-ups?

    TG

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