Feedback/Advice? Raising the Gunnels/Extending the Freeboard

Discussion in 'Fiberglass and Composite Boat Building' started by cdre, Oct 27, 2010.

  1. cdre
    Joined: Jul 2010
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    Location: Iraq

    cdre Junior Member

    Looking for feedback and advice. I'm looking at converting an inboard ski boat to a fishing boat. Original thread here.

    Since this is a relatively low freeboard boat, I'd like to raise the gunnels for safety and to allow the boat to be used in the slightly more choppy conditions of salt-water flats.

    The thought is to cut the hullsides the full length of the boat say halfway between the chine and gunnel. I'd then cut the rear of that upper section away from the bow section about 2/3 of the way back. Raise the stern section 6" or so, slide the bow section forward and realign at 12" or so above where it previously was (I'd like a little more height up front). Feather from the inside and use some sort of a smooth pliable material to serve as the form between the various hull sections to which the new fiberglass would be bonded. I'd end up removing the dash and most of the closed bow to fiberglass in a few storage compartments and a casting platform, so the cap up forward would be modified heavily, and the gap between the cut front and rear gunnel sections would just be laid with fiberglass.

    I know it's an ambitious project, but inboard is the way to go for not spooking tarpon, and one can get a fully operational freshwater only ski boat with trailer for less than 5k. Put some money into mods, and you have a fast boat perfect for the type of fishing I do.

    I'm specifically looking for feedback on construction methods... I've replaced rotten decking before, but nothing like this. Any ideas on what I should use as a mold to receive the fiberglass?

    Here's an example of the boat I'd like to modify. An '80s Mastercraft 190 (fiberglass stringers at '83 and up).

    Thanks!

    [​IMG]
     
  2. cdre
    Joined: Jul 2010
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    cdre Junior Member

    Here is a (very poorly) photoshopped idea of what I am shooting for... Don't laugh too hard.

    Any advice on layup techniques, materials, mold materials, ect would be most helpful.
     

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  3. cdre
    Joined: Jul 2010
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    Location: Iraq

    cdre Junior Member

    I'd like to achieve lines similar to this Scout.

    Any recommendations on material to use as a mold? Layup schedule and procedure? Thanks!
     

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  4. Landlubber
    Joined: Jun 2007
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    Location: Brisbane

    Landlubber Senior Member

    cdre,

    There is no need to make a mould to put a simple fishing deck onto the boat, just remove the old deck and make a new wooden frame, gun'le and carline, deck beams and then cover with marine plywood and sheath in epoxy /glass (woven). It will be very cheap to do compared to making a mould and will last many years.

    Raising the freeboard is another matter, I would suggest that you simply buy a boat with a higher freeboard, but i you insist on this one, then use a simple thin plywood former on the outside of the hull, do all the glassing up to it, then grind off the plywood, revealing the structure in solid glass, a simple bog fairing over this will recreate the same shape and flow, just higher.
     
  5. mark775

    mark775 Guest

    Do you have melamine board there? Screw it right to the hull with sheetrock screws. This a big job.
     
  6. TeddyDiver
    Joined: Dec 2007
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    Location: Finland/Norway

    TeddyDiver Gollywobbler

    What you are intending is a major reconstruction and easy to go wrong with it IMHO. I'd recommend something more "light" and safer way. Raised rails on stanchions and a board on the sides as an additional bulwark. Some painting..
     

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  7. cdre
    Joined: Jul 2010
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    Location: Iraq

    cdre Junior Member

    Thanks for the responses. The idea is to build this in Belize (I'm only temporarily in Iraq), and yes, I can just bring melamine board from the states.

    What should I use as a layup schedule?

    Thanks!
     
  8. mark775

    mark775 Guest

    There are better people to respond to that than I. I would just lay up until it felt right and a little less than what is there but lay up with a shelf to set the cap on. I'll repeat that this is a project not to be taken lightly and remember that with the extra freeboard, you need to design in extra freeing ports ( a way for shipped water to leave the deck). You don't want this thing getting too heavy up top - I wudn't bother with a core unless there is already in the sides but the foredeck should be light (cored - good quality plywood will be about as light as you are going to get) and attention paid to every ounce of materials.
     
  9. cdre
    Joined: Jul 2010
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    Location: Iraq

    cdre Junior Member

    I definitely appreciate that it is not a small project, but I plan on designing/building this boat for a specific purpose and keeping it for a very long time.

    Extra freeing ports? Are you referring to scuppers? I had given that some thought, but I'm not sure where the waterline is relative to the deck, so I'll have to look into that later.

    On the cloth, any specific recommendations on type of cloth for structural strength? I figure a couple of layers of chopped strand first (so when fairing I don't sand the woven) followed by a few layers of woven cloth. All laid against 1/4" plywood with melamine tape (avail 24" wide) and a release agent. Figure the tape/release agent should give a relatively smooth surface requiring limited fairing. Will I need to apply a layer of fiberglass on the outside of the joints as well, or will a layered application to a one side be sufficient?

    Thoughts? Thanks!
     
  10. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    You can buy a used fishing boat in good condition for the price of materials to modify a ski boat. Are you looking for a hobby or a boat? There is a difference. If you are looking for something to do, it is possible. However, if the lines of the hull extension follow the existing ones, it will have a ridiculous amount of hook forward. You should cut the hull down first, and then fair an extension. Those hull have a thin foam core, so it is not so easy to work.
     
  11. Stumble
    Joined: Oct 2008
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    Location: New Orleans

    Stumble Senior Member

    Cdre,

    I just can't see any advantage to performing this modification as opposed to buying a reasonable boat for what you intent to do. Not only is the cost of such a conversion likely comparable to the cost of the right boat from the get go, you also have the long period of time it takes to perform the work, a boat with virtualy no resale value, serious questions about hull integrity and the quality of the work, ect...


    As for your stated purpose of fishing for tarpon... I have caught lots of tarpon on outboard engines, and my uncle won the Grand Isle Tarpon Rodeo a number of times fishing from a 26' wellcraft with twin outboards.
     

  12. oops!
    Joined: Oct 2007
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    Location: kelowna bc

    oops! Junior Member

    i recently took a 69 searay srv 190 and extended the hull out to 24 feet, i also considered adding to the freeboard.

    bear with me here, as i have a few thoughts for you.

    number one......if you want a project.....thats a good one. very expencive....but a good one.

    if you just want a good fishing boat in beleze.....nost of the guys there are running pangas....you might find that that hull design is far superior for those waters and purpose than the mastercraft does.

    you could sell the mastercraft and get more than enough money to buy a panga with twin outboards on.....as the economy in Belize is low....so your 12,000 bux will go a long way......even in fact as far as buying ocean front land there.....then you will just need a fishing pole....no boat ! :D

    ok.....if you do want to do the renovation.....what you will need to do is

    a... extend the freeboard off the edge of the hull cap. (that is a shoebox type hull/cap joint) you would go straight up with the glass however far you wanted to.
    your cap would fit as before....but you would need to purchase new steering cables as well as throttle control and engine wiring harness, (unless you only go 6 ins or so..but then...whats the point of the addition?)

    this would give you a really weird looking boat, and kill its resale value.

    b. you could cut the hull as you suggested...and use the lines of the boat ...continuing with the forward rake of the hull....
    to do this you will need to extend the edges of the cap.....as your cap the way it is will just fit like a lid of a pot that is too small.
    also ...the cap will also need to be cut from bow point to stern and extended beam wize.
    you will also have to redesign the interior as well.

    the above is a lot of work bud !......its your boat....you can do what ever you want with it.....but be prepaired....what you will have when you are done......is a remodled mastercraft that wont be worth much money.....and you will see the guys in the boaston whalers or the pangas taking the surf just fine.....and your flat bottom will be slapping along.

    in answer to your questions about what type of mold and layup schedule.....
    the mold should be thin plywood (1/4 inch) with arbourite over it.
    this will give you the rigidity you need with the flex you will require to fit the hull lines
    the waxed arbourite over the plywood will give you mold release and flat surface to gellcoat.

    the lay up schedule would be....(glassing minimum one foot below the cut line)
    (interior of hull)
    1 oz csm against the interior of the hull and arbourite.
    then a 1708 bi ax and keep alternating till you have 4 wraps of 1708 alternating with the 1oz csm.
    (make sure that you cut the 1708 and lay it so the grain of the material is paralell with the edge of the hull....if not the top edge will fray and make a real mess)

    for the extension of the hull cap perimiter....use the ply and arbourite use the same lay up schedule....but you would only need to go three layers of 1708 with the csm between.......this will give you the stiffness you need for the hull cap....(you will also need to add strips of wood under the deck on edge and glassed it the under side of the top deck...these will run latterly.....the width of the beam.

    you can just gellcoat as uasual after fairing the extension areas.

    there ya go bud......good luck.
    bear in mind....this is a lot of work...at least 10-15 gallons of poly resin..a full roll of 1708...and a boat load of money and time
     
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