Custom Extended Swim Platform

Discussion in 'Boatbuilding' started by tpenfield, Jan 8, 2019.

  1. tpenfield
    Joined: Dec 2016
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    Location: Cape Cod, MA

    tpenfield Senior Member

    That's brilliant !!! :D:cool:

    I think that will work quite well. I guess I'll be returning the deck plates I bought.
     
  2. tpenfield
    Joined: Dec 2016
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    Location: Cape Cod, MA

    tpenfield Senior Member

    Hardware Update:

    The weather has not been cooperating, but I am making progress on the hardware. . .

    IMG_2733.JPG

    I still have to finish the strut fasteners underneath.
     
  3. fallguy
    Joined: Dec 2016
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    Location: usa

    fallguy Senior Member

    Looking good.

    I am still wondering how it is nonslip is all.

    Maybe I forgot.
     
  4. tpenfield
    Joined: Dec 2016
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    Location: Cape Cod, MA

    tpenfield Senior Member

    The non-slip pattern is in the mold. It is the slightly raised areas that you see on the platform and the hatches.
     
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  5. tpenfield
    Joined: Dec 2016
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    Location: Cape Cod, MA

    tpenfield Senior Member

    I had some difficulty with the hardware mounting on the transom/swim deck side of the strut mountings, because I ran into a couple of pieces of wood that were molded into the inside glass of the built-in swim deck. So, rather than trying to use a electrician's fish wire, I cut a couple of access holes in the bottom of the existing swim deck.

    IMG_2736.JPG

    I was able to get the mounting bolts installed. 7/16" SS bolts . . . 3 on the transom side and 2 on the extended platform side for each of the 4 struts. I have some deck plates to seal up the holes.

    I also added pop-out cleats on the sides.

    IMG_2737.JPG

    Still need to install the rubrail, but I should be done soon. :)
     
  6. tpenfield
    Joined: Dec 2016
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    Location: Cape Cod, MA

    tpenfield Senior Member

    Finished !!! :) :) :)

    I got the remaining items done on the platform today, so it is ready to go. There are still a couple of tweaks, but nothing major.

    Here are some pictures of the final form . . .

    IMG_2753.JPG

    IMG_2750.JPG

    IMG_2751.JPG

    IMG_2744.JPG

    IMG_2758.JPG

    We will be 'load testing' it over the 4th of July holiday weekend. :D
     
    fallguy likes this.
  7. missinginaction
    Joined: Aug 2007
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    Location: New York

    missinginaction Senior Member

    Won't it be fun. You know, when someone asks "Who did the swim platform for you?" and you can say "I did." Impressive job. The only other comment I'd make is to be sure that you sealed up those access holes you made in the bottom of the platform really, really well. You'll have a lot of water slapping and sloshing around under there. Congratulations, you've become skilled with the goo for sure.
     
  8. tpenfield
    Joined: Dec 2016
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    Location: Cape Cod, MA

    tpenfield Senior Member

    Thanks for your words of praise. I'm looking forward to launching the boat and using the extended platform. And yes, the deck plates are the screw-in type (not the pop-out). I used 3M 4200 on the threads of the deck plates to screw them in, so that it would make a good seal and not come loose. Also the flange is sealed with 4200.

    IMG_2747.JPG
     
    Last edited: Jun 25, 2019
  9. tpenfield
    Joined: Dec 2016
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    Location: Cape Cod, MA

    tpenfield Senior Member

    I was contemplating adding a piece of rubrail in the area between the ladder struts. I decided to do so. Here is an updated picture.
    IMG_2765.JPG
     
  10. tpenfield
    Joined: Dec 2016
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    Location: Cape Cod, MA

    tpenfield Senior Member

    The boat is in the water. The platform looks to be OK, as I was hoping it would be a few inches out of the water.

    IMG_2774.JPG

    IMG_2776B.jpg

    There does not seem to be any issues with 'tail dragging' or anything like that when coming on/off plane.
    IMG_2770.JPG

    We are hoping to get some good use out of it this summer. :)
     
    gonzo likes this.
  11. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    I think you should start over, it should stick out another 3”.


    It looks great.
     
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  12. Deering
    Joined: Feb 2005
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    Location: Juneau, Alaska

    Deering Senior Member

    I haven’t read through all of the discussion so apologies if this has already been brought up... One small note of caution is your exhaust. If you add a lot of weight to that longer ‘lever arm’ you just added to your stern, say a bunch of people stand on it, make sure your stern doesn’t sink to the point that water goes over your exhaust risers and floods your cylinders. If it looks questionable, you might want to consider high lift risers to eliminate that risk.

    A friend learned this lesson the hard way after overloading their swim step.
     
  13. tpenfield
    Joined: Dec 2016
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    Location: Cape Cod, MA

    tpenfield Senior Member

    Good point. I'll have to see how high the current risers are vs. the waterline and the height available in the engine compartment. I know there is a Mercruiser installation specification that puts the risers at a certain distance above the static waterline. I'll have to go look that up to see how much leeway there is.

    To your point, there is more room for people to sit/stand at the rear of the boat with an extended platform.
     
  14. tpenfield
    Joined: Dec 2016
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    Location: Cape Cod, MA

    tpenfield Senior Member

    I found the Mercruiser Spec for exhaust risers in the manual.

    IMG_2793.JPG

    13 inches to the top of the exhaust elbow, probably gets to 9-10" of height to the bottom of the inside of the exhaust elbow. Wave action along with a bunch of people on the stern would make things a bit iffy. I may see if I can go with a 3" riser, when I do my next exhaust maintenance.
     

  15. tpenfield
    Joined: Dec 2016
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    Location: Cape Cod, MA

    tpenfield Senior Member

    I took some measurements of the boat/waterline with no load. I got 20.5” (a), 5.5” (b), making (c) = 15”.

    With load the boat goes down in the water about 3-4”, so the (c) measurement becomes 11-12”, which is shy of the spec. I’ll see about adding a set of 3” risers to bring it up beyond the spec.
     
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