Dry Strip Planking

[Wrekin]

Thank you very much, redreuben, for your detailed post. Do you happen to know if the builders are still around? It would be interesting to hear how they felt the dry build went compared to the wet build and of course to see if they compared the final weights of the three boats...

Okay, so an epoxy putty was used to glue the strips together. I agree, Fall guy, that important to get the hardness similar to the wood for easier fairing.

Does anyone have any rough ratios of epoxy to micro balloons and silica that they'd be happy to recommend I start off experimenting with?

Hmmm, interesting that double bias for the exterior was chosen, effectively doubling the fabric weight of the designer's original spec...

Ooh, and finally, was a male or female mold used?

 

[redreuben]

Great post from r/r.

I’m gonna reiterate one thing I have experienced in various areas of building.

If you use a very different hardness glue compared to the wood selection; when you go to sand the hull fair; the wood hogs in before the glue and very hard to ever get a fair surface.

And just to be thorough, this phenomenon is magnified when planking in foam.

 

[redreuben]

Thank you very much, redreuben, for your detailed post. Do you happen to know if the builders are still around? It would be interesting to hear how they felt the dry build went compared to the wet build and of course to see if they compared the final weights of the three boats...

Builder was lost in sailing in South China Sea.
The three cedar hulls all had moulded decks and teak/timber fit outs but I have no idea about weight.

Okay, so an epoxy putty was used to glue the strips together. I agree, Fall guy, that important to get the hardness similar to the wood for easier fairing.

Does anyone have any rough ratios of epoxy to micro balloons and silica that they'd be happy to recommend I start off experimenting with?

If I'd remembered I would have posted, roughly you add microballoons to get as much bulk as possible then a little bit of silica to hold the slump.

Hmmm, interesting that double bias for the exterior was chosen, effectively doubling the fabric weight of the designer's original spec...

Ooh, and finally, was a male or female mold used?

The cedar hulls were built male, the FRP hulls female, the early FRP hulls were foam sandwich with a vinylester skin, a one off (racing) special was built in 100% VE and post cured.
After my departure I believe hulls went to coremat.
The FRP hulls also had all glass keel grid and frp interior mould.

 

[i_mac]

Hi Rob. I am the current owner of the former Riverside Oaks (now Dux Nutts). I am doing a repair on the rear beams and any information you might have on the construction details would be welcome.

When strip planking was common in Aus (I was supplying epoxy to 30 builders of cats over 30' long within 30 kms of my shop and was only the third largest supplier), at least one builder planked dry, then glassed. Cut outs showed the resin had wicked all the way through the join. PU foaming glue had only just appeared and was a better option than applying epoxy to the planks.
We built a boat (Riverside Oaks, 8m Grainger tri, 1987) in female moulds. It is truly painful. Set up fairing requires pushing the batten onto the frames rather than draping them over. Stepping over the frames was tedoius and easy to miss and possibly knock things out of fair. Working on your knees for the shaped planks along the bottom was painful and slow. Ian used female moulds because they suited his sheet foam technique foam. Not many strip boats were built after he realised the benefits of foam, possibly not worth his time changing the plans? I strongly recommend a male set up for strip. If you are unsure, build the floats first, using female, then decide for the main hull.

AFAIK, I built the first Paulonia (kiri) strip planked boat in Aus. Had to wait for the trees to be harvested. 35' proa, 8mm planks, 200 gsm uni either side. Washed up on the beach by big waves in a storm, no damage. It is nicer to work than cedar, lighter, not as toxic, rot resistant and does not soak up water like balsa does. Does not look as good clear finished.

Riverside Oaks had 6mm glass uni across the planks. 400 double bias around the dagger case. It is still going strong, despite a pretty hard life. The first large strip plank boats were built in NZ. 30' tris with similar laminate over 10mm planks. Also still going strong, afaik.

Truly rough cut is hard to work with, needs to be cleaned up. Resawn (big bandsaw) is fine.

Use bulkheads where possible instead of frames and/or leave frames in when turning. You only need a couple to keep everything rigid.

In humid conditions glass the other side as soon as you can, or it may move.

 

[rob denney]

Lucky you, it's a great little boat. I have no memory of how the beams were made. Sorry.

The correct repair is to replace the beam, or at least the damaged section near the pin. Before doing that, carefully grind back the damaged area and see how deep the damage goes. Maybe the unis along the beam have not been too damaged and the solution is to wrap it with a couple of layers of +/-45.

Is the damage from sailing loads? Where is the boat?

 

[i_mac]

Lucky you, it's a great little boat. I have no memory of how the beams were made. Sorry.

The correct repair is to replace the beam, or at least the damaged section near the pin. Before doing that, carefully grind back the damaged area and see how deep the damage goes. Maybe the unis along the beam have not been too damaged and the solution is to wrap it with a couple of layers of +/-45.

Is the damage from sailing loads? Where is the boat?

Hi Rob,

Thanks for getting back to me. Yes, the damage is from sailing loads - no collisions. The boat is in Adelaide - I sail out of the RSAYS. There is a small group of enthusiastic multi sailors here - half a dozen tris plus one 8.5m box boat cat and a few cruising cats. Our major regatta is the annual King of the Gulf in Port Vincent. KOG https://www.myasa.asn.au

Once I have the boat sorted, the plan is to do some campaigns on the East Coast. Fingers crossed for Airlie 2026.

cheers