Fiberglassing 15m wooden fishing boat

Discussion in 'Wooden Boat Building and Restoration' started by Giorgos, Jan 29, 2012.

  1. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 490, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    I generally agree it's not good to 'glass a hull, particularity one as thick as this, but a deck on a workboat, yep, it's the best thing you can do. A plywood substrate and 'glass sheathing is the tightest, most waterproof deck going, for wooden boats, regardless of build method. On a carvel, you can really firm up a weak and tired hull, just with a plywood deck, so just imagine the advantage of having this on a relatively new hull.

    Work boats take a beating, usually daily, which requires some tough decisions about the weather decks. Honestly, the best thing you can do to a carvel is keep sweet water out of her bilge. A plywood, covered in heavy 'glass deck, does this very well.

    As for the hull, the planking is too thick to consider the usual sheathing options. This said, you can apply a sheathing, but it will need to be especially thick. Personally, I'd wait on the hull sheathing, until you run out of other options, but the deck will do nothing but benefit from a plywood sub deck and heavy sheathing.
     
  2. Giorgos
    Joined: Nov 2011
    Posts: 13
    Likes: 1, Points: 3, Legacy Rep: 27
    Location: Greece

    Giorgos Greek fisherman

    Thank you guys.There was a mess in my mind about this issue.
    Never believed that internet forums can provide so much help!!!
    Once we solved this issue i need some info about paints.
    What kind of paint for the hull?Something that lasts longer?
    Remember timber is iroco.Many told me that is difficult timber for paints.
    And something else.Before she goes back in the water the guy that owned the
    shipyard told me to use sikaflex rubber insted of putty for the keel-plank gap.
    I did it.Is there anything wrong with this?I have no experience in wooden boats.
    Shall i take it off next time she's out and replace it with something else?
     
    Last edited: Feb 5, 2012
  3. Giorgos
    Joined: Nov 2011
    Posts: 13
    Likes: 1, Points: 3, Legacy Rep: 27
    Location: Greece

    Giorgos Greek fisherman

    Where are you friends?:confused:
     
  4. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 490, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Iroco can be painted, but is dependent on the prep and just like all of the oily woods, needs special attention. The surface needs to be well toothed (sanded or better if scraped) then sterilized and de-oiled. Once cleaned a good quality epoxy primer applied as soon as the solvent s flash off. Over this can go any top coat. If your painter isn't discussing a cleaning, with a solvent wash first (not mineral spirits), then they have no idea how to handle these types of wood and you should look elsewhere, for a painter that understands the prep necessary, in these types of wood species. I'd use a mixture of acetone and toluene, possably with some isopropyl tossed in.

    You have a lots of choices in regard to paint, some a little more durable then others, but typically at a substantial cost, in both application labor and materials. If it was me, I'd stay away from the LPU's and stick with a much more economical single part polyurethane. You'll get nearly as durable a paint system, at a greatly reduced cost, with easier application and nearly the same gloss/UV inhibitor retention.

    A lot of traditionally built boat owners come to regret using a modern polyurethane in the seams, instead of traditional caulk and seam compound. Yard workers like this stuff, because it's easy to apply, but more importantly, they don't have to live with the boat. Come the next time you need to caulk the boat, removing the SikaFlex (292?) you'll pay dearly, as it usually is so difficult to get out of the seams, you end up damaging them and have more work to do to clean them up for new caulk. Of course, if paying a yard to do these things, then it's a win/win for them, as they'll absorb the additional labor costs too.
     
  5. michael pierzga
    Joined: Dec 2008
    Posts: 4,862
    Likes: 115, Points: 0, Legacy Rep: 1180
    Location: spain

    michael pierzga Senior Member

    Have a boatbuilder look at the Plank in question. This plank is generally the weak link in the hull. Fastenings become loose or the boat settles in shape. Pumping sikaflex into the joint doesn't fix the problem.

    The local trawler pictured just performed it yearly haul and replaced her Garboard plank then repainted topsides with common oil based enamel. Planks and paint are part of the yearly cycle of a wodden boat.
     

    Attached Files:

  6. Giorgos
    Joined: Nov 2011
    Posts: 13
    Likes: 1, Points: 3, Legacy Rep: 27
    Location: Greece

    Giorgos Greek fisherman

    Friends You Really Helped Me On This Issue.
    Next Time Boat Is Out Of The Water I Will Post Detail Pictures
    Together With Questions...thank You Guys!!!
     
  7. Nick.K
    Joined: May 2011
    Posts: 328
    Likes: 25, Points: 18, Legacy Rep: 103
    Location: Ireland

    Nick.K Senior Member

    Sheathed decks are certainly water proof, but also prone to rot.
    Be careful what plywood you buy. A lot of "marine" plywood on the market is about as durable as a mayonnaise sandwich. I have seen marine stamped plywood delaminate after a few days in the rain and last year I stripped out plywood cockpit where I could easily poke my fingers through the half inch ply. Good plywood is however surprisingly resistant...but expensive. Marine plywood from Allin (http://www.allin.fr/) is probably as good as any you can buy.
    You will have to be obsessive about preventing water from passing the fibreglass (through edges, fastenings and damage), once the sub-base gets wet it will never dry out and problems will be inevitable in the long term.
    I spent nine months, every day on the water as a charter skipper in the Greek islands, have many great memories of the places and people.
     
  8. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 490, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    The plywood deck, as I've described is the recommend method and doesn't rot, plus it dramatically stiffens the boat. Skip any step, again in the described above, and I can guarantee nothing. Nick, one has to assume they'll use good materials, other wise we'll be chasing our tails in no time, attempting to explain things.
     

  9. Nick.K
    Joined: May 2011
    Posts: 328
    Likes: 25, Points: 18, Legacy Rep: 103
    Location: Ireland

    Nick.K Senior Member

    Par. I didn't state your method would rot. just that sheathed traditional decks are prone to rot. In general, they are.
    The OP may not decide to use your method as outlined, he may pass the work to a yard.
    He may feel that buying material as stamped for marine use is OK and think that he IS buying quality material (crap is often expensive too).
    . However you sheath an existing traditional deck with plywood and glass fibre (or zynol or whatever) and however you seal the plywood with epoxy, you will have a greater RISK of rot. If water enters and saturates the plywood through a fastening hole or a gouge or if there are voids under the plywood in the bedding compound which become saturated then rot is inevitable either in the plywood or the original deck.
    If Laun plywood gets wet, it rots fast.
    Impermiable coatings are great for keeping the water out but also for trapping it in.
    Is it unreasonable advice to be aware of these issues?
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.