Foam construction: flat panel and strip planked combination

Hi folks.

I've been lurking here for a while and have been enjoying the interesting and useful information that's shared here. Thanks to all those who contribute.

Having observed and studied a number of designs (for one-off builds) there's something that I haven't come across and I'm wondering why.
Simply put: flat panel construction with strip-planking in selected areas. I'm not talking about strip-planked bottom hull forms that are pre-built on a temporary male mould . I'm thinking about smaller areas, where a handful of planks could significantly soften the otherwise hard chines, or to facilitate nicer 'knuckles', etc.

I'm mostly interested in foam sandwich construction, but the principal is the same for plywood.

Dudley Dix employs his 'radius chine' method as a simple way of adding compound curvature, but it's limited to a mostly constant radius.

I also note the 'Spirited designs' method of kit construction, using mostly flat panel, plus pre-moulded (in a production mould) hull and deck transition sections. It's a great solution, but doesn't suit a one-off design.

The idea is a flat pack kit in the usual manner (laying hull panels over the actual bulkheads, mounted on a strongback), except the hull panels have gaps where planks will be laid afterwards to facilitate nicer transitions. Of course, extra stations/moulds could be temporary added to the inside, if required to keep the planking fair.
Seems very obvious to me, yet I haven't seen it.

Any thoughts, pro's and cons?

I can illustrate with a sketch if that helps.

Cheers.

 

Keith Callahan has some designs using flat ply panels with strip plank chines. Nothing new here. Same can be applied to foam.

 

Dudley Dix offers several designs featuring this technique and I believe the Australian designer who became Ben Lexcen created the Contender as a double chine design,with extra strips to be added to the bilge panel and shaped to a curve.

 

Jacques Mertens-Goossen's LB26 uses flat panels and some strip in all foam.

For those that did not know, Jacques passed away Tuesday, April 5. I will add an announcement to the forum when/if I find a public notice.

 

Here's a cross section through an arbitrary hull and deck. It could be a catamaran hull or an aeroplane fuselage. The concept is the same.



What I'm talking about is using a handful of longitudinal strip planks to 'soften' otherwise hard chines, even if only for aesthetic reasons. Yes, it would require fairing, but if the planks were laid with only an inner skin, they could be faired then glassed over (foam sandwich).
It's just not something I've seen from any of the flat pack kit designers. They tend to go for a mostly planked design, or an entirely flat pack design with little in between.
It's hard to believe that this isn't done, but I'm yet to see it.
DD uses the radius chine technique, which is great, but as mentioned, it only really caters for a constant radius along the hull. It also requires pre-fabricating the radius sections on a mould.

 

It should be noted that hull-deck and hull-sides configurations you have drawn may not be adequate for all vessels as the hull downforce can crush foam deck-hullsides intersections and same for hull bottom-hullsides.

Otherwise, reducing foam width or kerfing foam to make bends is a common practice; on the LB26, there is some tumblehome and concave bow sections and both use strip or kerf methods.

 

The LB26 looks great! Longitudinal kerfing of the main side panels has allowed for a very nice shape.


R.I.P. Jacques.

 

This is what I was thinking...

 

The boat has multiple techniques available, but foam is the only way to go.

 

I like it and agree with you about foam!
I suppose when doing this with foam, it's best to leave all the glass until afterwards.
I've seen some kit builds where kerfing of duflex panels was needed near the bow, where the required twist was too much for the flat panels. Seems a shame to slice up a glassed panel, only then to have to add more glass to put it back together.

 

Thanks for alerting the forum to the news of Jacques passing. His designs allowed a lot of people to experience the satisfaction of getting afloat in a boat of their own creation.

 

I built the seat-boxes on my boat this way. Ply panels on the sides and ply strips with filler to give me some nice radiussed corners.

 

yes, that's definitely the way to do it. I just hadn't seen this technique used along the full length of a hull, to soften chines, that's all.

 

This can be very handy when you want a midship girth that is a bit more than 2 panels wide, which is very common. It also allows you to run all the wiring harness and plumbing runs from the outside before you put the last strips on. That is very handy on small boats. You can also use a greater siding dimension to create a space-frame effect. Keel, bilges, sheers, and a king plank get you a six-sided longitudinal space frame on which to mount the flat panels and protect them from the most common types of dockrash.

see attch here Full-length keel https://www.boatdesign.net/threads/full-length-keel.27476/page-2#post-275930