Matthew Flinders 2410

[Joe Anderson]

Jay and Carol Knight built a Flinders 246.  https://messing-about.com/forums/topic/11017-mathew-flinders-246/

 

 

I really like this boat design and I was thrilled to see Kalos in person at one of the Messabouts

 

 

 

When I first spoke with Graham about my interest in this design I told him I wanted to build using marine plywood construction. Graham said I might want to consider foam core construction. I thought no way I want to stick with a familiar construction method. Over the next few months the idea of foam core construction started to work on me and the next time I spoke with Graham. I asked him what kind of foam core he would recommend.

Graham and Alan had modified the Flinders 234 to accommodate Jay's needs hence the Flinders 246. I sat down with Graham and Alan and we worked out some of my modifications as well as all the changes in tooling necessary to come up with a jig to build the boat using foam core. 

 

There are a few different ways to build using foam core but we settled on covering a male jig with foam core planks and then glassing inside and out.

 

 

 

 

 

[PadrePoint]

You’re never one to sit still. 
I was clear in myself that I’d not build another boat. But, I recently decided to buy Don Silsbe’s extra sail that needed a boat. My boys decided to build a simple project with me and to involve my grandkids as well: a 8’ B&B Two Paw that can accommodate Don’s sail. 
I told the kiddos that THEY would be responsible for its name and how it will be painted (now THAT could be interesting) and that they’d assist in the build. 

[Joe Anderson]

Ted, I like the way you include your family in your boat building. Should be a fun build and a blast to sail the Two Paw.

[Jknight611]

Congratulations Joe, good to see the new boat’s progress.  I am so very confident you will love the design.  I am here to help when you do the heavy lifting,  other than sanding…… 

[Joe Anderson]

Thanks Jay, I appreciate your leading the way with your build. I expect to benefit from extensive R&D.

I understand about the sanding. I guess that is why peel ply is my friend.

 

I think B&B make a pretty cool jig. This is looking forward from the inside. The hull is inverted.

[Jknight611]

That is a nice jig. For us the planking was rather amazing, it planked up so quickly that Carol started hauling galley supplies out to the shop.  

[Jonathan M. Cohn]

I'm excited to see her take shape. Does the jig become the structural bulkheads and just the planking is foam core? What about the decking?

[Joe Anderson]

After the exterior is glassed the hull will be flipped upright and the entire jig removed. The interior will be glassed. Interior bulkheads will be plywood. The deck, house, all exterior structures will be foam core.

[Steve W]

This will be fun to watch. And the idea of an insulated boat is very appealing. Skeena's condensation at night can be annoying. 

[Joe Anderson]

While it is certainly possible to add insulation to the interior of a boat regardless of the construction method, I liked the idea of the insulation being an integral part of the structure. Thermal insulation is one of the reasons I went with 1 inch foam, which is much thicker than what is necessary from a structural standpoint.

[Jknight611]

The insulation on Kalos is super nice.  The boat has been in a marina (mostly) for 3 years and no unusual smalls, drips, or condensation issues.  Building the entire boat with foam will be a game changer.  

[Reacher]

Joe, would you please share your “pros and cons” thinking that went into choosing foam over marine plywood and okoume plywood? Thanks.

[Joe Anderson]

Pros and Cons for building with Foam core construction vs marine plywood.

 

Foam core construction provides superior thermal and acoustic insulation. You can add insulation to the interior of a marine ply boat, but it's nice to have it built in.

 

Theoretically foam core could be lighter and stiffer, but that is not why I am building in foam core and I don't think the Flinders 2410 will be any lighter or stiffer than the 246.

 

Foam core is not susceptible to fungus. 

 

I think I wanted the challenge of a different building technique.

 

The foam adapts to curves easily and evenly.

 

Cons

 

Likely going to take much longer to build, but that is mostly the fault of this particular builder.

 

Foam board cuts and shapes easily, but it produces an unpleasant dust that clings to everything. 

 

Foam board requires a building jig.

 

 

 

 

[Jknight611]

Not sure if the foam you are using is the same as the foam that the Looper deckhouse is built from,  we sure got practice in stirring epoxy!  Seems like we were precoating a sponge.  The overhead of the Looper has some relatively large unsupported areas and after laminating both sides we could hold a square dance on the top!.  I will mention peel ply….

[Joe Anderson]

Interesting about the epoxy absorption. I haven't noticed what I would call excessive epoxy uptake. I think that is related to the cell size. The cells are closed the absorption occurs in the spaces between cells. Manufacturers mention absorption, but I don't remember seeing any way it was quantified. I am using Corecell which is a SAN based foam. I think you said you were using a PVC foam.

 

What type and amount of glass have you got on the Looper deckhouse?

[Jknight611]

The Looper deckhouse is PVC foam with 1708 biaxial glass, single ply on the inside, single ply on the outside with up to 4 ply where some components with be mounted.  

[Joe Anderson]

How thick is the foam core on the Looper deckhouse? And since you are working with plywood construction and foam core, would you have anything to add as far as pros and cons of the two construction methods?

[Jknight611]

The foam we built the deckhouse with is 25mm which is very close to an inch or is it vice versa? After a brief introduction I agree it is some cool stuff to work with.  You will enjoy it.  Once you pre coat and first layer of glass, no difference. 
 

I may have cheated somewhat.  I have some areas that are a little tight radius for the glass to want to follow the foam.  This technique is only applicable in Southern Mississippi,  and I assume no responsibility if it makes a sticky mess, (that’s what a rasp is designed to cure).  There, that’s said..

After some of my tighter radius areas precoat had gelled I took little 1/4 X 3/4 ish inch long pieces of basting tape to hold the glass into place till I could saturate it with epoxy.  Sure made it more manageable not to have the glass 8 feet from you in a pile on the floor.  Tried industrial sized straight pins with some success but tiny pieces of basting tape worked great. Tried blue masking tape but that seemed to pull the glass out of column.  The tiny pieces of basting tape seemed to disappear/disolve/or just go away after saturated with epoxy.