Taped Seams

[wentzzee]

OK tell me fellas ...........this tape seam ...stitch &glue or however you say it....

I like the design of the bay river and core sound 17's but I a pretty hefty fella at 6" 285 now just how sturdy is that compared to a conventional ply on frame type construction???? I would hate to step into it and have it fall apart under me. Or is it I need to change with the times?

[capt jake]

Plenty strong when it is all finished. During the construction phase (as with anything) they can be a bit flimsy feeling. But after all of the pieces are properly fitted and installed, they are quite solid.

In addition to Grahams designs, just to prove a point, take a look at Devlin's boats. They are all S&G (stitch and glue), and he has them up to 40 feet!

http://www.devlinboat.com/

Welcome BTW, I saw you over on the BYYB also!

[wentzzee]

Capt Jake

Yea im getting real serious about starting now got all kinds of stuff gathered up. BTW arent you the fella with the same name?

[Joe Nelson CS#35]

I am about the same size...The structure is not a concern. What is a concern is the total weight of all passengers and gear. I opted for the CS20 because it will carry me and my family better and go faster.

The taped seams when done properly are stronger than the wood they are attached to.

[capt jake]

BTW arent you the fella with the same name?

That would be me.

[JeffM]

The seats as designed might want a little reinforcement. I weigh 200lb and didn't want to have to tip-toe too much, so I added transverse 1x2s such that there was no more than 14-16" of seat between frame members. You might test the stiffness ahead of time by standing on a piece of 1/4" ply with strips underneath at different distances to test spacing, realizing that the actual seats, supported on all edges, will be a bit stiffer. Graham has pointed out that, with the grain running across the seats, a longitudinal stiffener would be more effective than my transverse framing. Finally, if I remember right, another member of the forum went with 3/8" ply for his seats.

As for boat size, I can't see an issue. More important might be the number of your crew. I had Beatrice Ann (CS20) out last in 10kt+ with a total of 2 large adults and 3 children and we fairly flew! On the other hand, without that weight, I'd have had to reef.

[wentzzee]

Thanks guys crew size isnt an issue because I only forsee a crew of one. I was just wondering about the structural integrity of the taped seams. I wouldnt want to have to go down with my ship. I'm looking to do a lot of camp cruising and need to trust my vessel.....thanks again

[Greg Luckett]

The taped seam usually is stronger than the 1/4 plywood itself. Try an experiment of epoxy and tape on seam butted together at different angles, then when cured, try breaking the pieces apart. My experience was the plywood breaking outside of the taped area, and that after putting one side in a vise and prying the other side with a cheater bar and wrench.

[PAR]

Basically the fillet covered with tape is a composite brace. The brace dimensions can be calculated and usually replace a structural member, such as a stringer or knee. This is why stitch and glue (tape and seam) designs can be so strong, with few structural pieces (ribs, longitudinals, etc.) With well placed furniture, covered fillets and a bulkhead or two, the hull structure can become a homogonous unit. This is a reasonably new type of engineering, but a sound one with examples of it in every aspect of society. If you'd like I can post the math necessary to figure out the strength a specific covered fillet will impart.

[Joe Sundstrom]

Let's discuss the taping of the OUTSIDE seams.

I have seen commercial sources of stitch and glue craft tape the outside of hull seams both before (Chesapeake Light Craft) and after (Devlin) completely fiberglassing the hull.

Which one is advantageous?

[Designer]

Joe, it all depends on whether you sheath the hull or not. For instance on my Diva kayak the seams are fairly close together so I prefer to just sheath the hull instead of tapeing and having to feather and fair the seams.

Each thickness of plywood needs a certain amount of glass on each side at the seam, so you can substitute a layer of tape for the glass sheathing. You just need to make sure that you finish with the same weight of glass on the outside of the seam.

The only caveat is if your design uses a specific fiber orientation. In dinghy's and kayaks you are using thin plywood so the seam loads are not very high but on larger boats a little extra glass won't hurt you so you could tape the outside seams per plan and feather and fair and then just sheath the hull with the material of choice.

[Guest Oyster]

OK tell me fellas ...........this tape seam ...stitch &glue or however you say it....

I like the design of the bay river and core sound 17's but I a pretty hefty fella at 6" 285 now just how sturdy is that compared to a conventional ply on frame type construction???? I would hate to step into it and have it fall apart under me. Or is it I need to change with the times?

re to your inquiry offline:

The taped seam issue eliminates framing and also weight in a hull. The glass works in conjunction with the hull scantlings to create a hull, not bullet proof the hull. In conjunction with the two components, there maybe some issues of fracturing the plywood, which is the most common component in tape and glue building. In liteweight construction, there are also components added to transfer loads across a greater area such as bottom thwarts, stringers fore and aft, and deck component parts, which adds rigidity to the hull, keeping or minimizing the twisting and loads applied to the bottoms. This is not to say that a person of your size cannot be subjected to stepping through all parts of a liteweight hull, even with the speced out components, so some reasonable precautions should be considered in deciding if a hull is right for you.

Fracturing a deck or bottom, truely has little to do with tape and glue seamed construction, and more about the thicknesses of the actual scantlings that you apply your particular weight to for your decision making process.

Many, if not all plans and designs, being sold now, are created with the mindset of how lite but surely strong enough can a hull be built and hold up longterm, to go the fastest speed for the hull bottom.

On the opposite end of the coin, a boat built oversized can also be unsafe in a sea, as the boat will not float properly and act right, on the limited amounts of bottom or surface area of displacement, and also can cause harm to the individuals when placed in compromising seaway conditions. The proper terminolgy is walking a fine line in overbuilding and creating enough margin of error that the hull hold up overtime and numerous launchings and various conditions.

I hope this has answered your inquiry, from my limited knowledge of boat design. As I am just another novice with no pedigree. So take these words with a grain of salt. You may want to consult with Graham with your concerns, too.

[Greg Luckett]

Doing a little "catching up", Oyster?

Good input as usual.

Thanks

[Guest Oyster]

Doing a little "catching up"' date=' Oyster?

Good input as usual.

Thanks [/quote']

I will reply to any and all reasonable mails unless it makes me a better man at my age. :wink: I may not do so if its posted on the net. I am consumed in making dust right now. :wink: I also have double duty at the homefront during my waking hours right now. Thanks.

[Tom Lathrop]

Graham,

I think that what Joe is referring to is Devlin's video in which he puts the fiberglass sheath on BEFORE the tape is put on over the seams.

I much prefer our method of doing it the other way round so that the tape edges can be faired down first before sheathing. If the tape is put on over the sheath, there is a danger of sanding through or at least into the sheath when fairng the edges..

[capt jake]

Graham' date='

I think that what Joe is referring to is Devlin's video in which he puts the fiberglass sheath on BEFORE the tape is put on over the seams.

I much prefer our method of doing it the other way round so that the tape edges can be faired down first before sheathing. If the tape is put on over the sheath, there is a danger of sanding through or at least into the sheath when fairng the edges..[/quote']

I am thinking that there are segments of the video that may be dated. I have never seen the video, but we are presently putting on the tapes first, fairing and then sheathing.

[Tom Lathrop]

Graham' date='

I think that what Joe is referring to is Devlin's video in which he puts the fiberglass sheath on BEFORE the tape is put on over the seams.

I much prefer our method of doing it the other way round so that the tape edges can be faired down first before sheathing. If the tape is put on over the sheath, there is a danger of sanding through or at least into the sheath when fairng the edges..[/quote']

I am thinking that there are segments of the video that may be dated. I have never seen the video, but we are presently putting on the tapes first, fairing and then sheathing.

I always meant to ask Sam about that but always forgot when talking to him. But hey, even old dogs can learn new tricks. LOL