Re: Stringer Question, Board Vs Plywood
Re: Stringer Question, Board Vs Plywood
Went across the border today to Detroit to pick up my supplies. In Canada my choices are limited. The guy who runs the shop said his recomendation would be to go straight to the 1708 and not bother with the CSM. My origional plan was to use 2 layers of each. Should I stay with the 4 layers ?
hi.....arch has you going in the right direction.
lets see if i can clear up some stuff.....
first....you need to read some......frisco boater has great stuff on his link.....
at the bottom of my sig......there is a link.....it is the most comprehensive fiberglassing instruction and detailes on the site. the first sixteen pages will do for now.
they guy at the store was wrong.....this is not a matter of opinion....but fact....(damm industrial plastics and paints.....the kids there just dont know)
chopped strand matt must allways be layed first next to a sub straight...(though its true that the 1708 bi axe has csm on one side).....its strand is stitiched and there for will want to follow the heaver weave of the thicker materal.... and not stay tight against the sub straight.
the way to MAKE THE FIRST ALL IMPORTANT BOND TO PLYWOOD...is to use unwaxed poly resin ...mekp at 1.5%....wet out the wood thoroughly....a dry plywood will want to make the resin skip over it....slop that stuff on.....and brush or roll it in several different directions. wait till the resin STARTS to get tacky.....then lay the csm over it and glass as per normal.......you dont want to go over kill with too much resin here...just use enough to wet out the matt....then use your resin roller to get rid of any air bubbles. add more resin if needed. the proper resin mixture you are looking for is 50-50
one layer of csm and 1708 is good enough, 2 layers of each is great, three is way overkill......1708 is super strong. in fact......3 layers of 1708 is as thick and as strong as your hull
I have a friend that has offered me 1" mahogany that would work for my 2 main stringers. Should I take him up on this and use them as my main stringers? The price is right (free) . My 2 main stringers measure 5.5" by 12 ft. I was going to keep them 1" in width.
the maghoney will be too oiley.
i use standard exterior grade plywood. the plywood has waterproof glue....and enough layers to keep me happy.
one of the issues that you will run into is wrapping the fiberglass overtop of the stringer......you will get air as the csm does not like to take sharp corners.....and the 1708 is way worse.
at best....you will be able to run the 1708 up the sides....but not over top. capping the stringers with csm is common.
as far as bedding the stringers...you can use peanut butter....(a resin cabosil mixture.....the recipe is in the link in my sig) or the pl glue.....understand....if you use the pl glue....it must reach a full cure before you glass over it. for this reason...i like the pb mix.
it is also important that you not lay the stringer directly on the hull.... it needs to be shimmed above the hull a wee bit...popsicle sticks on the flat work great......for this reason...you do not have to "v" the bottom of your stringers.
oh.....by the way.......you asked about the uneven surface of the transom hull......
after grinding.....there will be un even patches in the hull thickness....read the instructions in my sig for the transom installation...however......over the skin.....using a trowel.....screed pb over the hull.....this will fill any voids....then over the wet pb....you can start to do the transom lamination ....i suggest a fiberglass bond rather than a pl glue bond....the fiberglass bond will have more contact points and will in fact make the transom a part of the hull.
side note on grinding...... most builders do not know how much to grind.........what you are doing here is cleaning the fiberglass and removing the top layer of resin....this will expose the fiberglass in the hull matrix......i call it rough and scuff....you are just basically scuffing the fiberglass to ensure a good bond between the new and old layers.
hope that clears up a few things..... carry on.
cheers
oops
