68 flatback 222 rebuild

[Ulysses485]

Hey bro, good to see you getting back after it! I did see your message on my post about the stringer heights. I will need to grab reference dimensions from the transom to give you an accurate reference but I upload some dimension pictures that I took of a few weeks ago when I was looking into how much room I currently have for a fuel tank below deck. I will post the pictures to my build thread and a little explanation.

[Ulysses485]

It's been a while but recently started working on the flatback again. The starboard stringer bow section was actually completely delaminated and I decided to cut out the old stringer system and go with Kaycell 25lb. density. I have an old note of measurements from my stringers that says the original was 11" from hull to top of stringer. Just wondering if anyone can confirm this because it's been a while and I forgot to check before cutting out. I plan to raise the sole 2.5" and want to make sure I cut the new stringers at the right height was thinking 13". That would leave me approx. 16" from top of sole to the top of gunnel. Does this sound about right? Thanks

Should be putting a layer of 1708 on the entire hull bottom and installing stringers in the next few weeks. Will post updated pictures when done.

It would be my suggestion that you put at least 2 layers of 1708 down on the entire hull if you are going with a more traditional stringer design. One thing I noticed is that these hulls are laid up really thin. The overall design of the hull includes a trapezoidal stringer. I think by eliminating this stringer type and going to a thin (3/4'' to 2'') straight up and down type stringer (if that makes sense) i think you don't have the load spread out like you do with a trapezoid therefore causing heavier and more concentrating loads and a fairly thin laminate. Additionally, I would assume your going with 4-stroke modern power on a bracket with a lot more weight than the hull was originally designed for. Again, just my opinion and some food for thought.

[IRBflatback68]

That makes sense, I was planning on a layer of 1708 and a layer of 1.5 csm. I have a whole roll of each and plenty of epoxy. Not sure if I want to use all that 1708 on the bottom of the hull. Do you think a layer of each would be sufficient? Or should I just bite the bullet and double up the 1708 on the bottom?

Also going to fill the deep spot in the bow with a piece of kaycell and foam under it like many others. Should I cover the whole hull with glass first then add this? or will the 4 lb. Foam be good against the original hull then glass the whole hull over the filled in area after?

Thanks for the suggestions!

[Ulysses485]

I honestly cannot speak from first hand experience gutting stringers out and I am no pro....this will be my first 222 flatback build. With that said, these are just my thoughts. I think it really comes down to your stringer grid system. With enough bulkheads and spans over the larger span areas, I think you might be ok with one layer of 1708. I think the layer of 1.5oz wont really help as its not really a structural glass. It will just add weight and thickness. I would want the last layer to be of a structural glass. That's what you typically see in the bottom of hulls anyhow. One build comes to mind is from Dirtwheels (https://classicaquasport.com/smf/index.php?topic=4582.0). Check it out. He has a nice stringer grid system and it looks like he actually went with a layer of 1708 in the chines and then a layer of 1708 over the whole bottom and back to the chines again.

[RickK]

If you want to go a different route than trapezoid for the stringers, Lilrichard went the foam route - https://classicaquasport.com/smf/index.php?topic=957.msg8649#msg8649