Andrew, Reincarnation had many foam bulkheads. The foam was low grade and the deck stringers were set directly into it with insufficient'engineering' long-term. The tops of these bulkheads were removed and replaced with 4mm ply I-beams. No stringers were necessary as the I-beams supports the 4mm deck, not the foam. dkd suggestion of applying (6oz?) glass to the ply will work, espescially on the underside were it will be under tension when loaded, crew sitting on it. Applying it to a flat sheet then bending it to the required curvature will place all the 3 layers of veneers under tension that may result in some splitting. Applying another layer to the upper surface will bind this top veneer. You will have to consult dkd about any support of the deck, ie. bulkheads/stringers. I can email info on the construction of the I-beams if required, yes can be slow but NO deck failures of the 4mm ply after 17 years of some serious sailing.
Tortured ply is clearly beautiful. Mozzie 1765
Loc: Lake Bonney, SA
Guess your choices are getting endless, all of us are happy to help if required.
As for your paint issue, My other boat is painted with International/Awlgrip for the simple issue that it can be rolled and tipped off. Much much easier if you don't have access to spray booth or not wanting to piss neighbour/landlord off. Each has a purpose, and this boat has been done in International/Awlgrip for just the reasons you state.
The down side of International is the lack of colour choice, Awlgrip is a little better, much wider range and can be rolled and tipped off and stunning when done properly.
So I have 'almost' removed the top ply section of the composite deck on the port hull. I have kept the beams attached for now, as it keeps the hulls nice and stable, so I haven't removed the 50mm section of deck next to the beams. Its taking me aaages, I borrowed a friends battery powered Ryobi laminate router, with only 1 battery that lasts about 15 minutes, so its slow going, but they say slow and steady...
The foam between the two pieces of ply isn't a uniform thickness, it has been shaped to increase the curve of the deck. Whilst the lower sheet is curved slightly, it isn't curved as much as the top section was, so I am a little concerned that if I was to install stringers into the existing foam bulkheads (there are no stringers at the moment), the decks wouldn't be curved enough to measure as per the building rules:
5.13 The deck curvature shall be within 5 mm of the deck template as drawn on the plan but the gunwale may be radiused to a maximum of 3 mm.
That said, without a copy of the plans, my thoughts are if I create a template based on the existing curvature, and then use this when constructing I Beams, I should be OK.
There are currently 3 foam bulkheads between the rear beam bulkhead and the centerboard case. A couple of these have cracks which I will need to repair. There is a single foam bulkhead between the centerboard case and the front beams. I think I will add some more.
Philip, I would really appreciate it if you could send me the construction method for the I-Beams, my email is ASchnull@gmail.com.
Thanks again for all your help, I can't wait to get to the point where all I need to worry about is the color paint I choose
So I have removed the majority of the mid decks, and separated the hulls from the beams. I will be assembling a cradle tomorrow to hold the hulls level so that I can continue on.
It looks as if this boat had a hull replaced at some point. Foam bulkheads are in different spots, one deck was composite with no stringers, the other single ply with stringers. It looks as if the second ply sheet on the composite deck was added after some pretty rough repair work to the lower ply, and the foam used to raise the upper deck from the repairs. I have removed both ply sheets using a router, though unfortunately I will have to spend quite a bit of time sanding this flat.
My next move is to fix up / possibly replace the foam bulkheads, as a number of these are cracked, and most probably add some extras. Can anyone recommend a foam sheet supplier and the type of foam I should be purchasing? The existing foam is white, and roughly 25mm thick. I assume I should be purchasing some kind of closed cell foam, but want to make sure I purchase the correct one.
It also appears that the front ply bulkhead of the starboard hull has separated from the inside edge of the hull. The fiberglass tape on both sides of the bulkhead is sheared along the inside edge. I am not sure whether to try to remove and replace the bulkhead, as there is a roughly 5mm gap between the bulkhead and the edge of the hull in the top 100mm section of the bulkhead, or fill the gap, re-glue and tape it in as is. Unfortunately, I think this means I will either have to cut another hole in the deck forward of the front beam to get to the other side of the bulkhead, or remove the front deck section as well (there is already one hole but out when I needed to get to the chain plate).. I should have enough ply, I have ordered 2 sheets of 4mm gaboon which should be more than I will need for the mid deck replacement.
In regards to the I-Beams, it looks like in the photos that the foam is cut to the same level as the bottom edge of the timber strip which runs along the gunwhales, but I cant tell whether the ply strip is glued to the edge of the gunwhale, or to the underside?
So i have removed the decks, have started to replace a few of the foam bulkheads, and have also added a couple more. Although before I fiberglass the new foam bulkheads in, I just want to confirm that I purchased the right (or wrong) type of foam... I have used 40mm SL grade EPS foam sheet(Expanded Polystyrene), but further research has given me that sinking feeling (no pun intended) that I should have used XPS (Extruded Polystyrene)instead, as this is 'closed cell' and has a resistance to absorbing water. Is this correct? It shouldn't be too hard to re-cut the bulkheads from new foam, but I have no idea where to purchase this... Any suggestions?
I fixed the starboard bulkhead with an epoxy glue fillet (this epoxy stuff is really amazing). Next move once I have taped the foam bulkheads in will be to complete the ply I-Beam supports.
Loc: Lake Bonney, SA
I would have used a closed cell foam for the reason you mention, it does not absorb water.
Several sources, any good boat-builder should have sheets of it. A surfboard manufacturer/repairer or probably the easiest is to go to one of the composite material suppliers, FGI, Huntsman or Applied Composite Technologies and get good quality stuff, maybe like Durakore .... ask them for their recommendation.
Personally I would use the latter one, they have been in the business for long time and always seem happy to help. There is my "two-bobs" worth.
The older of our boats has glass of about maybe 4oz on the inside and 2oz layer on the outside, as Philip said, puts inside into tension and the external layer goes into compression and really does nothing much more than stop the outer ply layer from splitting.
Thought I would upload a couple of photos of where I am with the boat (its been keeping me busy most weekends since end of last season). The relatively simple tasks of 'redecking' the boat, ended up becoming a complete rebuild. It probably didn't need to be, but its kept me entertained. In hindsight I think I could have built a new pair of hulls in the time this has taken me.
I have replaced all foam bulkheads, the ply front chainplate bulkheads, starboard hull front bulkhead at the main beam and all stringers. Foredeck has been glued on in this photo. I have purchased some centreboards thinking I could pack the existing cases with foam to get them to fit, unfortunately the new boards were a couple of mm too wide for the existing cases, so I have removed them and will be installing new cases (as far back as rules allow, 10 degree angle). The old slots have been glasses up.
I am about to drill new beam holes, then send the aluminum beams (incl centre) to an anodizer whilst I glass in the new centreboard cases. Remainder of the decks will be glued on once the centreboard cases are in. Should be fairing and painting the hulls after that.