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  1. #1

    Default Bench seat replacement - aluminum hull

    My first project is a 14' Espadon boat (made by Peterborough I think). I have stripped out the old wooden bench seats and floor that the previous owner had put in and fixed up a couple of holes/cracks.

    Next up is building a replacement bench for the middle. The original construction had 6 braces riveted to the hull. You can see 3 of them in the picture. Two on the curve of the hull and one to support the top of the bench.

    The original braces are broken, and instead of removing them and riveting in new ones, I'm thinking of putting in a new floor and bracing the middle bench off of the floor + the existing brace for the top of the seat. This should provide the support to prevent the flexing in the middle of the hull and I would avoid having to put replacement rivets in below the water line.

    The new floor will consist of stringers screwed to the cross braces with ss screws to create a level base. On top of that, 3/4 " exterior grade fir plywood. The bench seat would attache to the floor across the width of the boat, and the top of the bench would screw into the existing top seat brace.

    I should probably add floation foam into the seat as well for safety and additional support.

    Any comments? I really don't want to replace the rivets and build new braces if I can avoid it.
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  2. #2
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    Default Re: Bench seat replacement - aluminum hull

    Ah common, get angry, rip it all out.. Clean it up and go make yourself a walk through. It's pretty easy really.

    Just take out everthing then run two stringers 12 to 18" appart from transom to bow, put your 1/2 A/C plywood floor in and pour foam. Once the foam is done, run a piece of 1 1/2 x 1 thin angle up each side and work your way up to the top shelf with 3/8 ply. It will take you about 3 good weekends to complete.

    By the way, you can get indoor/outdoor carpet at home depot in a pre cut roll thats cheap. It's really easy to replace it and your can buy 10 times as much compared to marine grade.

    Check out the attachments. By the way, you don't need to put the 12gal gas tank in like I did. With my Nissan 18 I figure I can get about 600 miles per tank. I filled it up once all this year!
    Last edited by sschefer; December 8th, 2010 at 08:17 PM.

  3. #3
    Moderator Bondo's Avatar
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    Default Re: Bench seat replacement - aluminum hull

    On top of that, 3/4 " exterior grade fir plywood.
    Ayuh,.... That's WAAaay to Heavy....

    1/2" will do the job you need at 1/3rd less Weight...
    3/8" might even work at 1/2 the Weight...
    Any Grease is Better,..... Than No Grease at All.......

  4. #4
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    Default Re: Bench seat replacement - aluminum hull

    Bond-o, This is the second go around. The first time I used 3/8 for the deck and 1/4 for the sides but there was too much flex in the gunwalls. You could see it flexing a lot during speed runs and when I hung the down riggers off it.

    Mine is a western, all welded so the last thing I wanted was all that flex producing cracks. The flex went away with the thicker material. It did add more weight but I still managed 24.5 mph out of a 18hp 4 stroke with at 9x9 prop near sea level, (GPS). The water line didn't change enough to concern me.

    Steve

  5. #5

    Default Re: Bench seat replacement - aluminum hull

    Good thing I didn't borrow a truck to go out and buy that 3/4" ply already and have to borrow it again to return it this weekend!! Hence the name - Getting_started.... Oh well, better now then figuring it out next spring when the boat is wallowing around on the lake. Thanks for the advice on the floor.

    Anybody have an opinion on bracing the middle bench using the floor instead of replacing the braces attached to the hull. I've looked into the floatation foam a little bit and I think with that in there it will be pretty solid.

  6. #6
    Moderator Bondo's Avatar
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    Default Re: Bench seat replacement - aluminum hull

    Anybody have an opinion on bracing the middle bench using the floor instead of replacing the braces attached to the hull. I've looked into the floatation foam a little bit and I think with that in there it will be pretty solid.
    Ayuh,....

    As long as the Sides of the hull are supported,... You can deal with the center seat, or lack of it, anyway you'd like....
    If the Seat was comprised of nothing but a Top panel, with 2 panels running side to side,.. In other words, forming an upside-down Channel,...
    It would provide Alot of Structure, without even touching the deck...
    The Key is to make Sure the Sides of the hull don't Flex...

    As for using Foam,.... I think you'll be Wasting your time, money,+ adding more Weight....

    I keep mentioning Weight for a reason,....
    You're starting out with a Tiny boat, basically a rowboat.... I gotta believe it's carrying capacity is somewhat limited....
    That said,....
    Everything you add,.. Wood, Metal, Foam, Fishing Gear, Motor,+ Everythingelse,..
    Including of course,Your body weight,+ that of passengers...
    Goes against the Weight Limit of the Hull....

    I just don't want you to build a Great fishing machine, only to be Over-Weight as soon as you step into it...
    Any Grease is Better,..... Than No Grease at All.......

  7. #7

    Default Re: Bench seat replacement - aluminum hull

    Quote Originally Posted by Bond-o View Post
    Ayuh,....

    Everything you add,.. Wood, Metal, Foam, Fishing Gear, Motor,+ Everythingelse,..
    Including of course,Your body weight,+ that of passengers...
    Goes against the Weight Limit of the Hull....

    I just don't want you to build a Great fishing machine, only to be Over-Weight as soon as you step into it...
    Hard to argue with that logic - I'm starting to come around. I was going to use a synthetic decking material for my stringers at first, then re-considered given the weight factor. I came up with square aluminum tubing but that can be somewhat pricey ($2 - $2.50/ft). Now I'm thinking about using 1 1/4" abs pipe. It's cheap, light and will definetely take the load structurally. Anybody have any other ideas for stringers that I might try.

  8. #8
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    Default Re: Bench seat replacement - aluminum hull

    "Now I'm thinking about using 1 1/4"

    Now that's a novel idea. What about using 2" ABS and ripping it down the middle. You can rip it on a table saw. I've done it many times. you could lay it cut side down and then use pop rivets to secure it to the hull braces. That would give you more surface area agains the hull and the pop rivets would keep it from side flexing.

    I my just try that myself.

    Steve

  9. #9

    Default Re: Bench seat replacement - aluminum hull

    I'll let you know. I'm going to play around with it this week to see how it goes.

  10. #10
    Captain Tim Frank's Avatar
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    Default Re: Bench seat replacement - aluminum hull

    Quote Originally Posted by Getting_started View Post
    Hard to argue with that logic - I'm starting to come around. I was going to use a synthetic decking material for my stringers at first, then re-considered given the weight factor. I came up with square aluminum tubing but that can be somewhat pricey ($2 - $2.50/ft). Now I'm thinking about using 1 1/4" abs pipe. It's cheap, light and will definetely take the load structurally. Anybody have any other ideas for stringers that I might try.
    Be careful on the ABS. There is lots of ABS piping that has little or no UV resistance.

  11. #11

    Default Re: Bench seat replacement - aluminum hull

    Is there a code on the pipe that would tell me if it is UV resistent or not? It shouldn't matter under the floor anyway though ?

  12. #12
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    Default Re: Bench seat replacement - aluminum hull

    Quote Originally Posted by Getting_started View Post
    Is there a code on the pipe that would tell me if it is UV resistent or not? It shouldn't matter under the floor anyway though ?
    It is true that ABS has no UV resistance. So what, you're not exposing it to sunlight under the deck anyway. If you're worried about it, paint it.

    If my motor lift ring comes this week I'll finish the work I need to do on my big boat and go back to work on my 14'. I've got a couple of lengths of 2" ABS DWV laying out in the shed so I'm going to give it a try too.

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