DIY cosmetic GRP mods; difficult? stupid? expensive?

Discussion in 'Boat Design' started by westie, Aug 9, 2011.

  1. westie
    Joined: Aug 2011
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    westie New Member


    I'm new to this site. I've been mulling over making some cosmetic mods to my ketch over the coming winter. Reason: purely aesthetics, because there are one or two areas that don't sit well with me when I look at her.

    This might be stupidity. As I have no experience with grp, it may well be beyond my technical ability ...and could well be more money and trouble than it's worth. I've done a couple of quick photoshop visuals to show the sort of thing that I'm considering (although these are by no means representative of the finished designs).

    Addition of a rounded storage box on the foredeck to reduce angular look.

    Addition of a sugar scoop to update the stern.

    Images on the left as she is now. Any thoughts?
  2. CatBuilder

    CatBuilder Previous Member

    While it's certainly possible, you will need to learn all the techniques (it takes quite a while, possibly more than the winter if you're part time). You will also need to build molds for modifications like that, where you have a specific shape in mind. Does seem like a lot of work and not worth the money. However, if you are doing it more as a hobby and because you love your boat, it may be worth doing for personal reasons.

    PS: I'm not a big fan of your first modification. You are modifying the boat so you have even less of a foredeck and an even bigger area to slip and fall on?
    1 person likes this.
  3. tunnels

    tunnels Previous Member

    Make the bits off the boat and then fit them . This will save you a lot of time and make it easyer and cleaner than trying to do the work on the boat . Make a mock up of the transom so the mew part can be fitted onto the old transom and then cut and finally glassed in possition Each part needs to be glassed inside and out side to give it good strength . Minimum would be 100mm scarf joins more if possible !!.Got the glassing schedual for each part sorted yet ??:confused:
    Good luck ;)
  4. CDK
    Joined: Aug 2007
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    CDK retired engineer

    The cabin mod is a lot of work both inside and out if you do it like in the picture. And I see no other purpose than a minor change in appearance: it took me quite some time to see the difference.

    The stern extension isn't just cosmetic, it is also useful.
    If you are satisfied with what you photo-shopped you can build the part in your garage, where you can provide the proper conditions for a good result.

    Instead of laminating (and grinding through the gel coat) you can put stainless bolts in the mating surface and use Sikaflex to obtain a watertight and clean seam.
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  5. tunnels

    tunnels Previous Member

    Sika and bolts !!!! What sort of a job will that look like !! Think professionally and do it like its meant to be like !!THE CURVED CABIN FRONT WILL SHED WATER QUICKER AND PUT LESS PRESURE ON THAT FRONT PANEL !!
    THE STERN IS A GOOD ADDITION TO BE EASYER TO BOARD AND STAND WHEN GETTING INTO A DINGHY OR WHAT EVER . Just remember all these addtions are structual and never loose sight of that point .they are there not just to look good but to be practical and usefull !!!:p
  6. CDK
    Joined: Aug 2007
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    Location: Adriatic sea

    CDK retired engineer

    It will look exactly the way Westie photo-shopped it, so I guess that's what he wants. For an amateur a bolted-on extension is already difficult enough.

    I extended my boat's hull that way in 2003 when I designed and built a twin tunnel drive. The extension carries the rudders, stern tubes and shaft supports, so it is very "structural". And I never even contemplated laminating it because it is a lot more work, more things can go wrong if the weather turns bad and it is harder to remove in case the results are disappointing.

    Besides, companies like Searay and Bavaria also use bolted-on parts like large bathing platforms and sections of the transom.
  7. whitepointer23

    whitepointer23 Previous Member

    so all the bolt on pods with large outboards hanging off them must be ready to fall off. there are thousands of boats with them.
  8. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    If this is an aesthetic considerations change, then I'd say you're not getting much for your efforts. On the other hand if the inside of the cabin gains more usable room and the sugar scoop is strong enough to serve as a swim platform, maybe you can justify the itching and cussing.

    Having just installed a sugar scoop addition to a sailboat, I can tell you it's a lot of fabrication if you expect to use it.
  9. westie
    Joined: Aug 2011
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    Location: UK

    westie New Member

    Thank you

    Thank you very much to all those who have replied to my post.

    Having read through all of the feedback, I have decided that it's unwise to proceed with this project, especially given that I have no experience with GRP.

    Although it superficially looks as though I'd be building simple shapes, the reality is that I'd struggle to achieve a good three dimensional match and/or a professional finish first time around I'd probably end up doing it three or four times. That sounds like a lot of time and effort for cosmetic changes. Yes, I'd gain a swim platform, but that's not a whole lot of use where we sail, as the water quality is often poor, and typically a bit on the cold side.

    It has been really useful to receive your input - so thanks once again!
  10. viking north
    Joined: Dec 2010
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    viking north VINLAND

    While you've already made your decision on this and a wise one I might add being in total agreement with the discouraging not to do posts however to reinforce your decision not to do i would like to add my two cents worth. The idea of a deck storage box while a good one does in reality raise your C of G and is just another convenient storge area to really erode it (C of G) over the years possibly to the un aware level that it would be that extra pound causing a knockdown. One must be very aware of the weights stored above the waterline especially on tender or smaller craft. Being old school I need not express my strong dislike of reverse transoms in following seas, it rates even greater than reverse sloped windshields and permanently fixed eyebrows for blue water work. That modification on her stern in my opinion you would again be eroding the sea keeping qualities of your vessel.

    A yacht is not defined by the vessel but by the care and love of her owner--

  11. Squidly-Diddly
    Joined: Sep 2007
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    Squidly-Diddly Senior Member

    make a foredeck box for extra PDFs and self releasing life-raft with related equip.

    In stern, have a nice stainless steel tubular ladder and mesh swim platform built as local welding shop, then bolt on. Its open structure shouldn't be too much problem in following seas.
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