Cabin top track

Message Topic Search Topic Options Post Reply Create New Topic Printable Version Translate Topic

   Hi, 

A crack has appeared in my cabin top in the corner near where the track for the lapper is mounted. The crack is about the same length as the track. Water is seeping in from the crack so the track must need rebedding since that is the only place I can think of that moisture could be coming from. 

You think a layer of glass will provide enough strength to repair this issue? Should I move the track a few inches so that it is mounted on the cabin side instead of the cabin top? 

thanks in advance, john

Author	Message Topic Search Topic Options Post Reply Create New Topic Printable Version Translate Topic
fatjohnz Members Profile Send Private Message Find Members Posts Add to Buddy List Commodore Joined: 05 August 2006 Location: United States Status: Offline Points: 296	Post Options Post Reply Quote fatjohnz Report Post Thanks(0) Quote Reply Topic: Cabin top track Posted: 28 September 2009 at 11:24am
	Hi, A crack has appeared in my cabin top in the corner near where the track for the lapper is mounted. The crack is about the same length as the track. Water is seeping in from the crack so the track must need rebedding since that is the only place I can think of that moisture could be coming from. You think a layer of glass will provide enough strength to repair this issue? Should I move the track a few inches so that it is mounted on the cabin side instead of the cabin top? thanks in advance, john

frfletch Members Profile Send Private Message Find Members Posts Add to Buddy List Commodore Joined: 13 May 2008 Location: Canada Status: Offline Points: 365	Post Options Post Reply Quote frfletch Report Post Thanks(0) Quote Reply Posted: 29 September 2009 at 12:52pm
	Given the short length of the foot on the lapper, any change you make in track position will significantly affect the preferred angle to the gib clew. I would not mess with that. It seems strange that a real crack would form there, but if so it may be owing to the ingress of water in which case you will have to do a repair anyway. Regards glassing, those barrel nuts, if original, and their respective screws are all under tension, so the only place that glass would do any good to improve the local structure would be on the bottom. A piece of glass tape on the top may be useful in preventing water coming in. If you think the situation is not too bad, why not try to dry it all up a bit (perhaps drill some holes in the top) then when dry fill the holes with high density epoxy filler and put one layer of 6oz. tape on top and fair it in. On the bottom, one could add more glass, or make up an aluminum plate to span all the screws. That will mean longer screws if the barrel nuts are to be reused through the plate, or longer screws in any case in order to reach an acorn nut. One could also use bigger washers under the nuts. The flange on those barrel nuts is not very big for spreading the loads. They do make larger diameter washers in 1/4" that could be used.

tprice Members Profile Send Private Message Find Members Posts Add to Buddy List Rookie Joined: 19 September 2002 Location: United States Status: Offline Points: 14	Post Options Post Reply Quote tprice Report Post Thanks(0) Quote Reply Posted: 30 September 2009 at 10:01am
	Fabricate a large interior backing plate to spread the load. Remove track and barrel bolts. Cover area along cabin top and side with duct tape. Wax - 4 coats. Lay up about 3/16 - 1/4" of glass and epoxy (or polyester) on a sheet of wax paper. Lay up should be about 4" longer than track and maybe 5" wide. Place wet laminate overhead on duct tape in track area (interior). Cover with peel ply (or wax paper strips).Have assistant cover laminate with duct tape strips longitudinally along cabin top and cabin side, stretched tight and adhered to cabin to hold laminate in place as it cures. Press into corner. IF you had to, you could use a stick to prop a tape covered cardboard, folded into the angle between cabin side and top to hold laminate to shape. When cured, peel laminate off and band saw backing plate to shape, clean up edges and paint. Install track with new, longer barrel bolts that are longer by the added thickness. (Jamestown Distributors). Dry out crack, fill with epoxy, re bed track and bolt all together. On my Laser 28, I found that the best athwartships location for the jib lead was outboard of the cabin top track. The deck track was too far outboard though. I ran an inhauler through the cabin top track lead, led aft to a 3:1 purchase and cleat on aft cabin top on each side. Sheet was led trough "floating block" on inhauler line, to outboard track on deck. Inhauler line was trimmed so lead was about over the windows. In puffs it could be played outboard to open the slot. This arrangement changed the load on the deck track to a shear loading and it seemed to take it fine. TP

Bill Layton Members Profile Send Private Message Find Members Posts Add to Buddy List Commodore Joined: 15 September 2002 Location: Canada Status: Offline Points: 551	Post Options Post Reply Quote Bill Layton Report Post Thanks(0) Quote Reply Posted: 30 September 2009 at 10:21am
	Obviously there is some damage to the glass under the gel-coat which needs to be repaired. Removing track, grinding out damaged gel-coat and glass to the foam core, letting foam dry out and then re-glassing and re-gelcoat will bring it back to the way it was originally without any added thickness. There will be no need for backup plates or longer bolts if done correctly. You don't need to use kevlar for this repair, even though you will be grinding some away during preperation. Just treat this as a standard fibreglass repair.

WarBird Members Profile Send Private Message Find Members Posts Add to Buddy List Skipper Joined: 25 January 2006 Location: United States Status: Offline Points: 92	Post Options Post Reply Quote WarBird Report Post Thanks(0) Quote Reply Posted: 30 September 2009 at 10:55am
	Doing an over head lay-up I have found a neat trick. Get medium or low density foam from a fabric/craft store. It is sold as cushion or pillow foam. 2" or 3" works fine. Cut a section that will overlap your lay-up by 1-2" all arround. Glue foam to a piece of plywood 1/4 to 3/8"" of approximately the same size. Cover the foam with wax paper or Saran wrap (plastic wrap). When you have wetted out your repair area and laid in you cloth glass, carbon, kevlar, basalt or whatever and wetted the cloth completely, press the covered foam against the repair. Clamps or struts wedged into position against the plywood backing plate hold the foam against your repair area giving a very even moderate pressure. Test fit your struts ahead of time. I used this process at my forward hatch opening when I replaced the wood between the skins there so I used C-clamps gently snugged. The platic wrap never stuck to the repair and left a nice smooth finish. WarBird

tprice Members Profile Send Private Message Find Members Posts Add to Buddy List Rookie Joined: 19 September 2002 Location: United States Status: Offline Points: 14	Post Options Post Reply Quote tprice Report Post Thanks(0) Quote Reply Posted: 30 September 2009 at 1:35pm
	Is there a wood block instead of foam in the jib track area in the cabin overhead? Or were barrel bolts sufficient to take the compresive load of the bolts?

Bill Layton Members Profile Send Private Message Find Members Posts Add to Buddy List Commodore Joined: 15 September 2002 Location: Canada Status: Offline Points: 551	Post Options Post Reply Quote Bill Layton Report Post Thanks(0) Quote Reply Posted: 01 October 2009 at 1:40pm
	Tom your absolutely correct. There is a small piece of plywood in there. Maximum 2" wide for the length of the track. If this is wet it's probably easier to replace it. Re-glassing the area will still overlap onto the foam core though. So the whole area will need to be dry Cheers Bill