Removing the Rotten wood - September 8, 2007

The plywood install by the builder was pine and not sealed, so over the years, getting wet and so forth if came down to being useless to repair. In speaking to a supplier for marine and MBO plywood, the cost is prohibitive for the amount that is needed. I will pose a question on sailnet and see if there is any alternative. (Answers varied, to no on your life to OK with expoy. Still need to see what would be the best solution as well as the true cost in long run.)

I have removed the foam blocks from the bow, for now, and cleaned the area. In cleaning, I have now seen all the areas inside that need attention. This is the only way that I know one can really get to know a boat. (Only repair in the front/bow of book is replace the berths). I will be instaling so shelves in the bow and then returning he foam blocks. The boat does not have a head and I would like. Pat want me to just have a portable pot. I guess that will have to do.

May need to replace the bulkheads, the wood at the bottom is rotted out. That will be a chore.

The 41, 30 and Westerly did not have the rotten plywood that this vessel has, so this is a new area for me. It not a problem as to replacing, having kept all the old plywood for templates.

Once the inside is ready to start rebuilding, I am going to pressure test the deck with water and Joy to see what has to be done.
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For future reference for the purpose by writer to have a quick source of information when needed. THESE ARE NOT THE WRITER but are attributed to other sources found on the Web.

Jim Seidel of Interlux doesn’t recommend applying any single-part topside paint directly over newly cured epoxy. Apparently, the amine blush, a common byproduct of cured epoxy, mixes with the driers in the paint and the finish won’t dry. Two-part finishes, like Interthane Plus, are less susceptible to amine blush. Better to allow the epoxy to cure for about a week or longer, then remove the water-soluble blush with soapy water and wet sand with 120-grit paper (always use 3M Freecut paper to prevent paper loading). As for a primer, it’s best to apply a blush-free polyamide epoxy, such as Interlux 404/414, then sand and apply the topside paint. To solve your problem Seidel recommends sanding well with 220-grit paper and wipe down with Interlux 333 thinner. Then try a small test patch, applying Brightside thinned 10% with 333. If it dries, paint the rest. If it doesn’t, sand to remove all the primer, then paint with 404/414 and Interthane Plus. This paint is a better choice for decks as it’s much harder than Brightside, but it cannot be applied over Brightside primer. The prior is attrituded to Interlux Paint.

The best method to attach fasteners where there is no back access and you cannot thru-bolt with a backing plate is to use the hardware bonding method. Bonding fasteners with epoxy resin (e.g. Epiglass, West System) increases the load transfer area to provide the needed holding power. Bonding techniques vary for cored and non-cored decks and for aluminum and stainless hardware. The following instructions are outlined in more detail in the booklet “Fiberglass Boat Repair & Maintenance” (catalog number 002-550), published and sold by Gougeon Brothers (Tel: 517/684-7286). Considering the point loading on a boarding ladder, you must prepare the hull and hardware exactly as outlined to ensure a good bond and prevent damage to the deck. To do this, mask the working area, then solvent wipe. Masking prevents contaminating the work area with wax residue, etc. Drill an oversize hole, twice the diameter of the fastener and to a depth of its length. To increase the holding power, fill the hole one-third full with epoxy thickened with colloidal silica. Let cure. Place the mounting brackets in position and outline the perimeter and fastener holes with a pencil. Drill pilot holes in the cured epoxy for the screws. Tape plastic around the work area to protect from spills. Using 80-grit paper, sand the area within the pencil line. Also sand the contact surface of the mounting brackets to expose fresh metal. Mask the finish surfaces of the brackets for protection from epoxy spills. Solvent wipe all mating surfaces. Mix up a small batch of unthickened epoxy and wet-out the matting surface of the deck, inside the drilled deck holes and screw threads. Wet out the mounting surface of the brackets, then aggressively sand with 80-grit paper. This exposes fresh metal in epoxy, thus eliminating air and the possibility of oxidation. West System also recommends etching the aluminum prior to wetting out (purchase the 860 Aluminum Etch Kit). Thicken epoxy resin with colloidal silica to a peanut-butter consistency. Apply liberally to the deck mounting surface. Fill the fastener holes and, using a toothpick or small stick, stir to remove any air bubbles. Liberally coat the screw threads with thickened epoxy. Place the brackets in position and tighten the fasteners just until epoxy begins to squeeze out the joint. Clean up any epoxy residue. Remove the masking tape. Allow the epoxy to fully cure at least 24 hours before attaching the ladder, and wait three days to a week before applying a load. The pror is attritubed to Interlux Paint Company.

Barrier coatings are designed to prevent blisters but the occurrence of blistering is unpredictable and subject to many variables. Chances are that, if your boat has been in the same geographic area with the same haulout schedule for many years and has suffered no blistering, it is not likely to anytime soon. Take the boat to a fresh water lake in Georgia and leave it in the water for 20 months straight and it might suddenly develop a blister problem. Some of the variables that affect a particular boat's proclivity for blistering include the quality controls on construction and materials at the time the boat was built, such as the length of time the boat has continuously been in the water and water temperature and salinity content. The next time you haul out have a surveyor inspect the hull bottom and check the moisture levels with a moisture meter after the boat has been out of the water for awhile. High relative (relative to the normally dry hull topsides) readings may give early warning of a potential for hydrolysis of the resin and the resulting blisters. In that case, you can dry the boat out and apply a barrier coating before the blisters have a chance to start. A barrier coat applied to a dry hull helps prevent blisters by preventing water migration into the laminate. Like an insurance policy, it's never a bad idea but you might not ever actually need it. The prior is attritubed to Interlux Paint Company.

According to Jim Siedel of Interlux, when a boat is not kept in the water there is no need for antifouling paint. Over time, however, the existing paint will begin to fade and chalk. This is an aesthetic problem only and, while it doesn't harm the hull, it may damage people's clothes if they come in contact with it. Use a paint remover (e.g., Interstrip 299E) to remove the coating. To remove the leftover stain in the gelcoat, blend 299E and 399 at a 50/50 ratio and apply while agitating the surface with a ScotchBrite pad. Next, compound the hull, follow with a glaze (e.g. 3M Finesse-it II) and then wax. These photos from Interlux show the steps involved. In the bottom photo, the boat looks brand new. If you decide to paint but don't wish to do this on a routine basis, Jim recommends using a hard paint, such as Fiberglass Bottomkote or Fiberglass Bottomkote Aqua, both of which retain their color longer than ablative or copolymer paints. The prior is attritubed to Interlux Paint Company.

There are several ways of going about this. While you could grind out an area so you have a 12:1 angle, prepare a patch that duplicates the laminate on your boat and bond the patch in place, there is a simpler method. Having just completed this on a 22' (6.7m) powerboat, it's very workable and the least visible. Use a holesaw to cut a plug from a piece of marine-grade mahogany plywood. The plug will need to be the size of the hole diameter you need to fill. Tape the repair area, and then solvent wipe it and the hole. If you have access to the interior bilge, do the same and sand with 80-grit to rough up the surface. Mix up a batch of epoxy resin, coat the edges of the plug. Glue the plug in place with glue thickened to a peanut-butter consistency. The plug thickness should be slightly less than the hull thickness at the hole. Position the plug so it's slightly recessed on the outside. Using a rotary tool (e.g., Dremel) and a cone-shaped file, grind the outside edge to create a bevel. Solvent wipe and fill the cavity with epoxy resin thickened with a mixture of microballons and cabosil. Level the area flush to the hull using a large squeegee. Wipe, sand flush, and then apply two or three coats of unthickened epoxy resin. As your repair is below the waterline and you'll be applying bottom paint, you don't even need to gelcoat. But if I was, I would sand, and then brush or spray on color-matched gelcoat. Once cured, remove the masking tape. Retape the repair area moving out 2" or more. Solvent wipe, wet sand, and then gelcoat. I usually move the tape out in increments a few times to blend in the repair. To stiffen the repair on the inside, solvent wipe, and then wet the repair area by brushing on unthickened epoxy, and then wet out a piece of 6oz fiberglass cut to size, lay over the area and use a squeegee to remove air bubbles. Once cured, cut your new hole and you're ready to install that new transducer. This is attributed to Jan Mundy.