D5 weight in 4mm?

[Justin Pipkorn]

A couple of ideas:
1. I am impressed with the S3 Silvertip resin and the way it wets out. Although I can't prove it, I expect one would use less resin than with the standard resin.
2. Who says you need to paint the boat? If you look at the various kayaks at pygmyboats.com, you will see lots of okoume plywood flowcoated with resin and varnished. We built two 40 pound kayaks and varnished over the resin. If you keep the boat out of the sun, the finish will last a long time. The finish is easy to repair. The pygmy kayaks are made out of 4mm okoume. Our kayaks had a layer of glass on the bottom and one layer in the seating area. The rest of the surfaces were just flowcoated. In order to have a painted surface look good, you will probably end of fairing and sanding a LOT. Then a primer is necessary followed by several coats of paint if you use the S3 paint. The S3 paint can be patched if you aren't too fussy but varnish is a lot easier to patch. On lookers see the beauty of the wood and don't see the blems in the unfaired surface. My guess is that the varnished boat would be much easier to sell than the painted boat.
3. I built a 7-3 pointy ended dinghy. I used 4MM on the side panels and 6MM on the bottom. I glassed the entire outside but only the floor area inside.

There were no frames. The seat tanks and laminated sheer rails provided ample stiffness. The dinghy weighed about 60 pounds.
4. As an idea of absolute minimum weight, I was familiar with an experimental 8 foot pram built by some aerospace guys. They used fiberglass and polyester resin at the time and a foam core. The boat was vacuum bagged. The weight was about 24-28 pounds.
5. If you could find it, I have seen some scrap Boeing surplus carbon fiber honeycomb panels used in areas where flat panels would work. Seats? This stuff is incredible.
6. Consider adding a slight bend to seats or other flat panels. On my dinghy, I used 6mm for the seat tops and added stiffeners on the underside.

[PJPiercey]

Looks great Kurt. I look forward to seeing it come together.

Paul

[Charlie]

The glass over foam idea shows up on this forum all the time. Will it work? Sure, but it's not as sturdy as plywood S&G unless there are enough layers of glass, particularly on the outside.The reason is marine foam, doesn't have the resistance to penetration offered by plywood so the foam has to have a lot of layers of glass laminated on. And all the extra epoxy (at 9¼ lb. per gallon)for the additional glass runs the weight up to that of regular S&G hulls which don't, necessarily, need any glass sheathing.

[Cascadie]

Charlie, I worked for Cessna Aircraft here in Bend, Oregon and we had sheets and sheets of honeycomb laying around, as well as G10 (premade glass panels) for our aircraft. All that stuff would be great on a boat, if you could get it cheaply! I love the lightweight of foam core boats, but the cost difference is just too great. And, there's just something about a wood boat that's in my blood.

I have almost made the decision to leave it bright on the outside, but you'll see why I might be leaning toward paint in a minute. I think I'll paint the interior a blue/gray with some anti skid additive.

I love the choices you made for your boats! I learned to sail in Naples harbor in southern California in a boat very similar to the D5 which they called the Naples Sabot. I think I was about eleven at the time. Any way, it's a class racing boat, and there are sails available from time to time in that area, sometimes very cheaply. It's hard to remember much from that long ago, but I do recall they were very happy times when sailing a Sabot. They just threw us (and a PFD) in the boats after a couple of hours of instruction and told us not to run into any big boats!

Ok, I have Silvertip resin and slow hardener and I'm really looking forward to getting some of that on, probably tomorrow. Here's today's progress, some of it very embarrassing:

Sides, transoms frames stitched together


An old saying comes to mind about measuring twice, sheesh. Notice the space where there should be plywood! This is the blood and the tears part, I didn't take time to photograph the sweat!


I'm thinking this is a good time to use the 5 minute epoxy.


I don't think it will look as stupid as it makes me feel. As good a shop as my BIL has, there was no board stretcher to be found.


Long story short, I got the GelMagic between the stitches, and I'm very happy. The boat is square within 1/8". An interesting footnote to it being square for others who might see this; Set it up on something so that the shears are resting parallel side to side, otherwise you'll see a large discrepancy in squareness due to the possible twist of the hull.


Going back later this evening to remove the stitches and fill in between with more GelMagic. The GelMagic was REALLY hard to squeeze out of the tube with a caulking gun. Anyone else run into this? It wasn't setting up in the mixing tube, either.

Did anyone have any thoughts on the gunwales in Mahogany? Do I have to steam them, lay them up in 2 pieces, or saw relief cuts? I'd really like to use this Mahogany instead of laying up ply, but they won't bend to the sheer at 19mm.

[Cascadie]

Answered my own question, half a strip at a time is no problem at all.



Something like this is what I have in mind, but with a wider spacing - more like 6 inches.

[Justin Pipkorn]

I would prefer using solid timber for the gunwales. If the sheer line is laid out correctly, you will probably be able to bend thin strips without having to torture the wood very much if at all. If the sheerline isn't lying in a plane, the visual effect of an S curve will be visible. Try laying a sheet of plywood on top of the sheer and see if it is flat. Joe Dobler who designed my Pepita shown above actually made a mold for the sheer for my boat. It was laid up of spruce and mahogany. In the first Pepita I built, I just laid up strips one at a time.

I wouldn't worry about the little glitch at the transom. Just make up a good story if anyone asks.

Are you going to add a sailing rig? Pepita used a Sabot mast dimensions and sail rig. You said that you sailed a Sabot early in your career. Now that you are a little larger than then, fantacize about taking down the mast while the boat is in the water! Unless you are striving for Sabot like performance, I think a simple sprit rig would work better. The ability to braile and reef the sail will allow much more relaxed sailing. At the Florida 120, I saw what I think was a gunter rig. I was surprised at how well these sails work.

I don't have the D5 plans so I don't know what the size of the dagger board is. The Sabot board in the water area was about 12 wide by 24 deep and that is a good size.

When you come to oars, check out my web site. http://www.amateurboatbuilding.com/justright/Chap17.htm I noticed that the pictures ar missing. I'll have to fix that. Make the oars as long as you can and still fit in the boat or about 7.5 feet.

There is also a rig for loading car top boats in the same chapter.

[PJPiercey]

Make sure you grind a nice radius to all of the outside edges that will get a layer of glass. Otherwise the tape will lift on either side of the sharp edge and develop air pockets. Because of this I do a lot of my spot welding with fillet material on the inside of the boat. I make the spot weld small enough so that the final fillet covers up the spot weld. Most all of the spot weld (and gel magic) on the outside will get ground off when you radius the edges.

Sure looks good . That's going to be a sweet fly fishing pram!

Paul

[Cascadie]

Not much to show for today, put in some of the fillets. I'm hesitant to round the corners til they're all in and glassed.

Justin that's funny I ran across your site while I was researching the oar building stage. I think I've settled on building these. Except that square section would carry the round all the way out to the handles. I like the high aspect ratio of these, and I'll round the tips more like an Aleut paddle or Greenland oar.


This site explains

I like that contraption for the boat loading! If the boat was going to be a fair bit heavier, I'd consider it. I'm thinking of a roller at the back of the station wagon which I would lift the fore transom to, then slide the boat forward and tie her down. Maybe even just a section of PVC pipe back there.

Paul that's what I was thinking, too. I'm going to let the fillets and glass on the inside set up before sanding them round(ish).

If this works, this is what I'm hoping to look like at completion, except no trailer.

[PJPiercey]

That paint job is a great way to hide the fillets but still show off the beautiful wood. People can't believe it's a "wood" boat when they see the smooth seams. I kind of did my V12 the same way.





Paul

[Cascadie]

Paul, that's gorgeous! I'm not going to shoot for that level of finish, I know it's way more work than I really want to do.

Today's progress:

Glassed all the inside seams and squeegeed one coat of epoxy inside.



Flipped it over and did the same on the exterior seams. All told, I believe I've used just under 2 pints of resin, but I haven't been keeping a strict tally. Fillets used far less paste than I had expected.



At the end of the epoxy ordeal, I cut out pieces for one of the oars. I'll cut out the other while epoxy is curing on the seat frames tomorrow. $28 of Ash. A substantial cost saving over buying oars, and much more therapeutic, plus - I get to choose the wood and the shape!