246 CCP fiberglass schedule - floor and transom

[kaptainkoz]

Hello,
I am going to apologize in advance for beating a dead horse  , and yes I have read about what to use on here for years, but now that im in the actual plan/purchase phase, I am having trouble finding the exact answers in searches so bare with me. Also, I think I have a unique angle in that I am trying to keep my purchases down to a whole roll of 1708 biaxial with 1.5 chopped strand backing, and a whole roll of 1.5 chopped strand.

1979 246 CCP floor... I am going to use greenwood XL 3/4 inch pressure treated kiln dried ply. I am using vinylester resin. I am fairly dead set on those two so I would prefer to avoid discussions on other core materials and resins as I have weighed many options and this is what I like. My confusion comes in at what are appropriate weights and fiberglass materials for the floor. I would like to buy a whole roll of 1708 biaxial with chopped strand backing and of 1.5 chopped strand as the costs are much less for a roll. I would like to do the underside of the floor with 1 or two coats of the 1.5 oz chopped strand just as a barrier layer being the 3/4 is plenty strong, and 1 coat of 1708 on the top side. Is that enough? I will be gel coating the floor. Should I do another layer of 1.5 over the 1708 to smooth out the imprint of the 1708 on the top side? Is 3 oz on the underside enough? What would be a suggested layup schedule for my floor?

2nd... Transom. I am going to gut the transom from the inside and close off the transom for a bracket. Do I need to reinforce the existing outer transom wall with 1708? If so how much? I am going to build an inner transom wall and pour the transom with 2 inches of Seacast where the bracket mounts, then pour 1 inch up to the cap. I am also dead set on Seacast so with that in consideration, what should be my layup for the inner transom skin?

Can I do all of this with just 1.5 oz chopped strand and 1708 biaxial with chopped strand backing?
I am weight conscious and do not want to over build the boat and make it heavier than it has to be, but of course I want it strong enough to not crack whatever I am installing.
So if you all could once again share your ideas taking into consideration what I stated above, I would greatly appreciate it!!!! :!:  :!:

[Tx49]

Hello,
I am going to apologize in advance for beating a dead horse  , and yes I have read about what to use on here for years, but now that im in the actual plan/purchase phase, I am having trouble finding the exact answers in searches so bare with me. Also, I think I have a unique angle in that I am trying to keep my purchases down to a whole roll of 1708 biaxial with 1.5 chopped strand backing, and a whole roll of 1.5 chopped strand.

1979 246 CCP floor... I am going to use greenwood XL 3/4 inch pressure treated kiln dried ply. I am using vinylester resin. I am fairly dead set on those two so I would prefer to avoid discussions on other core materials and resins as I have weighed many options and this is what I like. My confusion comes in at what are appropriate weights and fiberglass materials for the floor. I would like to buy a whole roll of 1708 biaxial with chopped strand backing and of 1.5 chopped strand as the costs are much less for a roll. I would like to do the underside of the floor with 1 or two coats of the 1.5 oz chopped strand just as a barrier layer being the 3/4 is plenty strong, and 1 coat of 1708 on the top side. Is that enough? I will be gel coating the floor. Should I do another layer of 1.5 over the 1708 to smooth out the imprint of the 1708 on the top side? Is 3 oz on the underside enough? What would be a suggested layup schedule for my floor?

2nd... Transom. I am going to gut the transom from the inside and close off the transom for a bracket. Do I need to reinforce the existing outer transom wall with 1708? If so how much? I am going to build an inner transom wall and pour the transom with 2 inches of Seacast where the bracket mounts, then pour 1 inch up to the cap. I am also dead set on Seacast so with that in consideration, what should be my layup for the inner transom skin?

Can I do all of this with just 1.5 oz chopped strand and 1708 biaxial with chopped strand backing?
I am weight conscious and do not want to over build the boat and make it heavier than it has to be, but of course I want it strong enough to not crack whatever I am installing.
So if you all could once again share your ideas taking into consideration what I stated above, I would greatly appreciate it!!!! :!:  :!:

I am going to piss you off by not answering your question but offering one comment about your material choices. Unless you are using the treated plywood because you have a line on some for free or close to it, I would suggest that you scrap that idea. Pressure treated plywood is full of voids that affect its structural integrity in boat building applications and the chemicals used can (I'm not saying will) cause the F/G to delam from the plywood over time. Properly glassed fir marine ply will outlast the treated. If you do not want the expense of fir over PT, then I suggest you use AC or BC grade pine plywood. It has better structural qualities and the resin bond on it will still outlast the treated. I know that many people have successfully used PT, but I also know that many people have survived plane crashes. Just because it worked out for them doesn't mean that its the best, good, or right way to land a plane. I am not telling you it won't work and that you are doing it wrong. I am just giving you something to think about. You may have already considered these and made your decision with full knowledge and I am commenting without knowing everything that went into your decision. Either way good luck.

[wingtime]

Ditto on the PT.  I read the Greenwood spec on the PLydeck PT.  That appears it is intended for use in non-fiberglass marine applications such say a  Pontoon boat deck.   If you want to use a Greenwood product you'd be much better off with their Boat Panel product: http://www.greenwoodproducts.com/store/ ... panel.html

[kaptainkoz]

Thanks Johnny and wing time, I do appreciate the information. I called greenwood in the past and they assured me that it can be glassed although, true, that the website isn't 100% clear on that. My reason for going for it is that I don't ever want to worry again about a leaking cutout or screw hole. True, you can properly glass plywood, encapsulate it and make it waterproof. However, I don't think it's a stretch to say that most plywood damage starts around cutouts and screws that are improperly sealed. As for strength, I'm not landing a helicopter on it. It's 3/4 ply, I'm sure it will be strong enough. If we were talking 1/2 inch ply then i would be more worried about integral strength. Even if it did Delam a bit, I'm sure it would take a while and I'm betting it would be barely a problem as the ply would still be strong, dry and intact.
 As for cost, here in Ny, greenwood xl is almost the same price as my local lumberyards marine ply. They want almost $100 a sheet for marine ply here which is about what the Greenwood Xl would cost delivered. I will call greenwood again and question them again about chemical reactions and Delam, but if their story hasn't changed then I'm going to go for it. I guess worst case scenario is I'm redoing a floor in the future due to Delam as opposed to doing a floor due to rot. Cost isn't much of a factor being I need 5 boards, so the $100 a board range isn't out of the question. I'm doing the work myself so I don't have any real labor costs to cover. I want to believe its a better product. In any event I will put more research into core selection.
Now.... How about my layup schedule?????

[gran398]

Koz, what is the cost of fir ply there?

Re the layup, your specs look good in terms of strength/longevity.

However, the Master Rebuilders know best, entrust them for final guidance.

[Capt Matt]

No PT no matter what they tell u, it will de lam
Lay up schedule minimum material:
One layer of strand on bottom of deck
1708 then strand on top of it on top side of deck
Tab inside of new transom with 1708 starting with small tabs then getting larger
Any place I planned on finish work on the transom i would go over the 1708 and cover with at least one layer of strand
A roll of each should be plenty for what you have planned
If your goal is to never have to do this again make sure you seal every screw hole, deck plate etc. the only real guarantee though is to  pony up and buy composite.
Capt Matt

[gon2sea]

all plywood use exterior glue, the only difference in marine ply is that there are NO voids. Lowes in my area carries very nice a/b 7 ply 3/4 plywood at about $33 a sheet, vinylester resin is great but not worth the expense unless you are doing bellow the waterline work. but if money is no object it really doesnt matter....
Eric

[RickK]

Koz, check this stuff out "plascore". It's a honeycomb type composite and costs about the same as marine plywood in 3/4" thickness. When you lam it up with 1 layer on one side and 2 on the other (like you would with any substrate) it becomes stronger than plywood. That's what I'm going with for my sole.

[kaptainkoz]

Thanks Matt. Well I guess that does it. I'd be a fool to turn down great advice and stay my course. I'm going to look into Douglas fir. Rick, I have samples of the nida core (like plascore) and coosa. I love the coosa but its $300+ a sheet! I am not a fan of the nida core honeycombs as its a pain to hold a screw. Sure, small hatches are fine, but for larger stuff like center consoles, t tops or leaning posts you have to create a plug in the comb. I do love how light it is. It is pretty amazing stuff! I did my own drywall screw pullout test on both. Nothing scientific, set a screw and pryed it out. I wasn't sold. I guess ill look into Doug fir now.
As for the resin, for the transom and stringer work i definitely want the stronger vinylester. The cost isn't too much more. The deck I can do in either poly or vinyl. Ill see what I have left after the transom. Thank you all for stopping me from making a mistake I appreciate it. For that I will share some well documented play by play. I love this site. I would not even think of doing a fraction of what I plan to do had I not spent hours on here seeing everyone else do it.

[Capt Matt]

Good luck with your project, the demo is the worst part.
Capt Matt

[dburr]

Sure, small hatches are fine, but for larger stuff like center consoles, t tops or leaning posts you have to create a plug in the comb. I do love how light it is. It is pretty amazing stuff! I did my own drywall screw pullout test on both. Nothing scientific, set a screw and pryed it out. I wasn't sold. I guess ill look into Doug fir now.

Koz for the big stuff mentioned above now is the time to plan.. Screwing a T into 3/4 Doug fir is a nothing deal unless there is some type of backing plate under it to fasten to or through bolt.  3/4 inch decking on it's own just doesn't have the thread depth for a wood screw to get e really good grab without going all the way through.  There is a pile of force on those T Top leg pads when you come down after blasting off the top of a 3 footer when you're doing 25...  If you are going to glass in a plug of G10 or other machinable material and drill and tap for a big machine screw that then that would make me worry less.. If you go to that effort, then you are back in the realm of using composites..


Guys have used sheet FRP and PVC, aluminum plate and G10 to name a few as backing plates.  Don't get hung up on fastening strength right into the core, spend some time sitting in the boat to figure out where stuff will go and build the backing plates in.  In the long run it will help spread out loads, prevent spider cracks and strengthen the boat as a whole..  By the time you're done, you will not want to do it again to the same boat unless someone is paying you..

I know you said you didn't want to get into it, my apologies for jumping on the soap box and flogging a dead mule..
 

[gran398]

Absolutely, you'll need strength on the deck to attach a T-Top. Although some boats aren't set up to install a T-Top...it is a great idea to plan ahead.

Miss D build...we imbedded Duralloy high density strips in the deck with regard to the T-Top install.  Shipoke also goes this route on their deck builds. If you go with fir....you can glass aluminum strips under deck, and tap...then bolt.

Or... you can forego the aluminum....and glass Duralloy (Penske Board or similar)  or ply in strategic spots beneath the plywood deck, and run # 12 screws sealed on the install.

[Capt Matt]

I did backing plates I glassed under the coosa deck to support my tower then did tap and die and 5200.
The tower is rock solid, good to know when you hit a speed bump or manatee at 35
Capt Matt

[kaptainkoz]

Great suggestions. Thank you. On the note of backing plates, has anyone thought of glassing plywood to the underside of the stringer? As the Stringer is cut open to get the foam out, couldn't you add a strip of plywood to the underside of the top of the stringer? Isn't the stringer on the 246 roughly where t tops and center consoles are bolted to? That may be a way to go as well.

[gran398]

Great suggestions. Thank you. On the note of backing plates, has anyone thought of glassing plywood to the underside of the stringer? As the Stringer is cut open to get the foam out, couldn't you add a strip of plywood to the underside of the top of the stringer? Isn't the stringer on the 246 roughly where t tops and center consoles are bolted to? That may be a way to go as well.

Don't put the cart before the horse. We did that, and glassed Duralloy (Penske Board) as stringer tops, assuming the T-Top would bond directly to the stringers.

It would have...had we run a factory-spec 38 inch console. Our console finalized at 28 inches in width...well inboard of the stringers.

Point is...pick the console width...then work to it. Not the opposite as we did. Added a hundred pounds....we ended up using the bonding surface to bed the tank hatch....but that was just luck.

Plan the work, and work the plan. We failed there...hindsight is 20/20.