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  1. #1
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    Default Up to no good: Bravo III thru hull water pickup

    Just looking for tips and advice from anyone who has done this conversion before ... or any advice in drilling a thru-hull. Never did that before either.

    Please advise:

    - I'm planning to glass in a piece of 1/2" plywood to reinforce the area. I was going to use regular construction plywood. Someone stop me ...

    - Is this transparent water hose good enough? I was going to use 1 1/4" wet exhaust hose but that stuff is ridiculously expensive and probably way overkill

    - Mercruiser flush kit: $160, plastic T valve: $9 ... why do I need to spend $160 on a Merc garden hose / flush kit? Its made of plastic too.










  2. #2
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    Default Re: Up to no good: Bravo III thru hull water pickup

    Bump, anyone done this conversion before? Looking for tips and advice... thanks!

  3. #3
    Rear Admiral Fishermark's Avatar
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    Default Re: Up to no good: Bravo III thru hull water pickup

    I did this conversion a few years ago - there's no way i would go cheap on this. Way too much chance of sinking!

    No bigger than the wood area is I went with a solid plank of hardwood. I also went with the proper thick reinforced rubber hose.

    And there's also no way I would use a cheap plastic tee fitting. Again - too much chance of the fitting breaking and the boat sinking. But that's just me.

  4. #4
    Rear Admiral Fishermark's Avatar
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    Default Re: Up to no good: Bravo III thru hull water pickup

    For flushing, why not simply add a quality brass strainer? You simply pop the lid and insert the hose and flushing is a breeze. Here's a pic of my set up:


  5. #5
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    Default Re: Up to no good: Bravo III thru hull water pickup

    Thanks guys.

    Its so tempting. That tee is $10 compared to Mercruiser's kit $160 ... both are made of plastic. Both USA made.

    Alternatively, I can go with an all-brass T / flush kit ... I assemble the parts myself for about $80.

    Fishermark - thanks for the pic. That'll get me thinking some more about this.

  6. #6
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    Default Re: Up to no good: Bravo III thru hull water pickup

    Quote Originally Posted by Fishermark View Post
    I did this conversion a few years ago - there's no way i would go cheap on this. Way too much chance of sinking!

    No bigger than the wood area is I went with a solid plank of hardwood. I also went with the proper thick reinforced rubber hose.

    And there's also no way I would use a cheap plastic tee fitting. Again - too much chance of the fitting breaking and the boat sinking. But that's just me.
    Here's the thing ... the Mercruiser flush kit for $160 is a "cheap plastic tee" ... the grey plastic one pictured above is only $9. Both are US made (if that matters anymore) ... and if you're talking wall thickness, the cheap gray one measures about .125" thicker.

  7. #7
    Senior Chief Petty Officer 04fxdwgi's Avatar
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    Default Re: Up to no good: Bravo III thru hull water pickup

    Quote Originally Posted by makonnen View Post
    Here's the thing ... the Mercruiser flush kit for $160 is a "cheap plastic tee" ... the grey plastic one pictured above is only $9. Both are US made (if that matters anymore) ... and if you're talking wall thickness, the cheap gray one measures about .125" thicker.
    Plastic fittings / cheap hose below the water line scares the heck out of me. Personally, I use brass / bronze fittings and heavy duty hose below the water line. If that fitting breaks, you won't know it till the bilge pump can't keep up and then it's way too late.

    Home supply chain plastic fittings aren't the way to go, IMHO..... I would even have replaced the MC plastic one with either a "glass filled polymer" (which the MC one may very well be) or bronze / brass one.

    The glass filled polymer fitting will look like plastic, is a form of plastic, but really isn't the same, and are as tough as nails. Sure, the cheap one will work, but for how long?

    I have alot of money tied up in the boat and saving a few bucks on a critical item designed to keep the water out of the boat just doesn't make sense to me.
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  8. #8
    Rear Admiral Fishermark's Avatar
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    Default Re: Up to no good: Bravo III thru hull water pickup

    Another thing to remember on the hose - this is a suction hose - not a pressure hose. You need a strong, stiff hose that will not collapse for the suction side.

  9. #9
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    Default Re: Up to no good: Bravo III thru hull water pickup

    Thanks for the advice.

    I'm going to ditch both the grey plastic T and the Mercruiser kit. I'm going for all-brass which will still be less than half of the Merc flush kit pictured above.

    Already bought some wet exhaust hose which I think is way overkill but it was sound advice.

    Thanks.

  10. #10
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    Default Re: Up to no good: Bravo III thru hull water pickup

    Thanks for the advice guys. I took it all...

    Return this Mercruiser kit, its plastic and costs $160


    Got rid of the plastic T and water hose...


    Upgraded to brass T and wet exhaust hose


    Got a piece of 1/2" maple for reinforcement


    Thru hull

  11. #11
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    Default Re: Up to no good: Bravo III thru hull water pickup

    Sealed with 4200


    Sealed the other end too


    Glassed in the maple plank


    Done.

  12. #12
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    Default Re: Up to no good: Bravo III thru hull water pickup

    Pm Opp's playing with hull's is his fortay..Or Ondarvr...Yacht DR..all are well qualifed. Hate to say this but i believe you have created a weak spot by not glasing and taping both sides of the injection unit. 5200 is great stuff but it is pliable not what you want under a hull at speed.
    Stickly a opinion your milage may vary.

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  13. #13
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    Default Re: Up to no good: Bravo III thru hull water pickup

    Yea I thought about that ... what if that thru hull catches a deadhead or at worst hits a rock right on the nose. Thats not 5200, its 4200. I figure the mechanical connection comes from the screws (which I'll replace with brass later) and the giant brass nut. I also completely glassed in that piece of 1/2" maple. Hopefully that gives me the reinforcement I need.

  14. #14
    Rear Admiral Scott Danforth's Avatar
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    Default Re: Up to no good: Bravo III thru hull water pickup

    you have already changed to brass, however the Merc part is glass reinforced (strong as hell) and the grey plastic tee is just resin (weak as hell). The brass will be a longer lasting choice. also, on the reinforced hose, make sure your using certified below water line hose, with two hose clamps at each connection.
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  15. #15

    Default Re: Up to no good: Bravo III thru hull water pickup

    I can't tell from your pictures, but it looks like you're mixing bronze and brass fittings. Stay with all bronze to eliminate galvanic corrosion. Also, tie it in to your bonding system.

  16. #16
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    Default Re: Up to no good: Bravo III thru hull water pickup

    Quote Originally Posted by undercover View Post
    I can't tell from your pictures, but it looks like you're mixing bronze and brass fittings. Stay with all bronze to eliminate galvanic corrosion. Also, tie it in to your bonding system.
    That is a great suggestion. But this is entering a territory I know little about ... what is a "bonding system?"

    This boat is new to me ... its a 5.7 + BIII .... it has a Mercathode which I will assume is some sort of corrosion inhibitor device though at the moment I have no idea how it works. There is a green wire going to each of the trim tabs. But for some odd reason, no green wire going to the leg.

    Should I try attach a zinc to it??

  17. #17

    Default Re: Up to no good: Bravo III thru hull water pickup

    You want all the metal pieces that have contact with the water to be electrically tied together. That's what those green wires are for On your tabs. Your leg is bonded with to the bellhousing via the flat washer with the little bolt in it (middle mounting stud on the left side).

    Just add your own green wire to your thru hull, and attach the other end to something else that's connected with other green wires (like a grounding point on your engine, etc.)

  18. #18
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    Default Re: Up to no good: Bravo III thru hull water pickup

    Update:

    Making a backet to hold the brass T and brass shutoff valve


    All stainless steel, drill and countersink 6 holes 10 guage, 1/4" angle stainless steel


    5/18 x 18


    SS bolts




    A means to attach this bracket to the bonding system of the boat

  19. #19
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    Default Re: Up to no good: Bravo III thru hull water pickup










  20. #20
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    Default Re: Up to no good: Bravo III thru hull water pickup

    Got the wrong size clamps









  21. #21
    Rear Admiral Fishermark's Avatar
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    Default Re: Up to no good: Bravo III thru hull water pickup

    And you were thinking of cheap plastic at one time???

    Good job!

  22. #22
    Rear Admiral Fishermark's Avatar
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    Default Re: Up to no good: Bravo III thru hull water pickup

    Although...now that I look at it again.... Not to "throw water" on what you've done, but I believe the ball valve should be attached directly to the through hull pick up in order to shut off the water in case of an emergency. The way you have it now if the hose should come off the through hull fitting your boat will sink in a hurry.

  23. #23
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    Default Re: Up to no good: Bravo III thru hull water pickup

    DUH ... why didn't I think of that.

    Good point, thanks for the input, I will make that change. But I'll need to special order a 45 deg FF 1 1/4 adapter for it.

    To be honest, I never thought about that possibility, I only put a ball valve there to allow me to flush the engine.

    Thanks! Looking for other suggestions ...

  24. #24
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    Default Re: Up to no good: Bravo III thru hull water pickup

    Just for future reference, what exactly is the point of the conversion? Is there a history of the B3's not having adequate cooling capability through the regular factory water pickup? I mean I wouldn't question it on a boat going 65mph+, but the B3 isn't rated for speeds over that, so . . . . enlighten me?!
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  25. #25
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    Default Re: Up to no good: Bravo III thru hull water pickup

    Quote Originally Posted by haulnazz15 View Post
    Just for future reference, what exactly is the point of the conversion? Is there a history of the B3's not having adequate cooling capability through the regular factory water pickup? I mean I wouldn't question it on a boat going 65mph+, but the B3 isn't rated for speeds over that, so . . . . enlighten me?!
    Um...Yeah. I can only get mine to go 57 mph with my stock 454!!

    My Bravo III works just fine with drive water pickup in 85 degree water (and I have closed cooling) and it picks up below the surface of the water so it doesn't grab anything that happens to be floating on (or near) the surface of the water.

    Any "stuff" that is floating on the surface that just happens to make it to the screen might go into the screen (and strainer) or if it's a plastic bag etc, might just cover the pickup........ Yes I know that's remote, but it does happen even with drive pickups (except that your drive pickup is on both sides of the drive instead of one place......
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