Tape both sides???

[Nockatee]

I have placed the bottom sheet on my punt. The middle 5.5ft on each side has inside wales and the bottom is glued and nailed as well as glued and nailed on the 4 bulkheads and stem and stern pieces. The seams where ply meets ply have been joined with a decent filet of resin in the inside and two layers of 6oz tape on the outside edges.
The question to the stitch and glue masters is......

Do I have to tape the inside of the seams? Will not doing so seriously compromise the strength of the bond?

Why do I ask? Doing so will require another order of resin and there aren't enough shekels in the "project account"

Thanks!
Nockatee

 

[gbinga]

So, where plywood meets plywood, on the bottom intersection, you have a fillet on the inside and two layers of tape on the outside, right?

 

[Nockatee]

Yes

That is correct. Also, the middle 5.5 ft of the bottom panel is securely attached with glue and nails to an internal chine log on each side.

I will try to get pics up tomorrow.

 

[tx river rat]

You need the cloth inside and out, the fillet isnt for structural strength it is to round the corner where the cloth can make the bend.
Ron
Fiberglass cloth doesn't like square corners

 

[Nockatee]

I was afraid that would be the answer. Oh, well. Need to find a few bucks for some more resin.

Thanks!

 

[seedtick]

go ask a welder if he thinks a fillet doesn't add structural strength to a steel joint - same analogy

don't know thickness of your sides or your bottom - but boats were (and still are) being built without any fiberglass tape at all

my Dad's bateau is 55 years old - 1/4" plywood, inside chine, no glass - i still use it and it doesn't leak

 

[oldsparkey]

I don't use the glass tape , just fillets and then glass the whole boat.

If I do use any tape it is over the center of the keel and from the top down or back till the bottom evens out. If there is a ridge all the way along the keel ( A "V" Bottom) then one strip over the whole joint. It is mainly for protection on the bottom from any wear and tear on it.

Chuck.

 

[JEM]

The fillets by themselves don't add much strength to wooden boat building. Alone, they act as a bonding medium to hold the wood together. If the 2 panels are at enough of angle and the fillet holds them in place, it would appear the fillet by itself is adding strength, but it's the orientation/angle of the panels.

The welding analogy doesn't make sense: You're not melting the wood. Metal has different surface properties than thickened epoxy or glue.

Add fiberglass coverage to the fillet and the angle formed by the intersecting panels, then you have significant increased strength. But all three work together to make that.

Always default to what the designer recommends.

 

[seedtick]

may not be melting the wood but you are doing an excellent job of bonding, if you don't like that analogy then,

Here's a c&p from Bertram Yachts publication

"Fillets in general

Fillets are the strongest reinforcement that can be added to a angled joint. As illustrated in the following diagram, the surface area of the bond is greatly increased, by the two contact sides of the fillet. The amount of this increased surface area is dependent on the radius of the fillet and the area of the primary bond line. The greater the radius of the fillet, the greater the increase in strength.



Let's say that in this case the bond line is 1/4" wide and 12" long, giving a primary bond surface of 3 square inches. By adding a fillet with a radius of 1", the bond strength is increased by a factor of 9 times, or 27 square inches.

The radius of the fillet should be at least equal to the width of the primary bond line, which would yield an increase of 3 times the strength without the fillet. Less than this, while it still increases the strength of the bond, the fillet becomes more cosmetic than structural.

Large radius fillets should be build up in stages, where as small radius fillets can be added in as little as a single step. "


They claim that the proper fillet can increase the bond strength by 9 times

I believe they have a lot more experience building boats than any of us here

 

[JEM]

Yes you can build a monster fillet to add strength but at what cost? More material? More weight? More expense?

A smaller fillet covered with fiberglass will have less weight, less material, less time to build, less cost, than a fillet "by itself" sized for equal strength.

Big difference between a yacht and punt. As the hull gets smaller, weight and expense factors are amplified. One size doesn't fit all.

The old ways are not always the best ways. Progress progresses.

Check the Betram site: http://www.bertram.com/hull.aspx

In fact, all high-stress areas, such as the chines and keel, are overlapped and utilize several layers of unidirectional S-glass for superior stiffness and strength.

Looks like they do in fact know what they are talking about.

 

[seedtick]

Don't want to get into a p***ing contest with anyone but the original question was about the "need" to put glass tape over the fillet.

I merely posted that boats have been built for years with chines and no fillets,epoxy, glass and have held up

Two folks posted that the fillets didn't add strength, I attempted to provide additional information that fillets do indeed add strength up to nine times for proper fillets and up to three times for a fillet that's the same size as the thickness of the wood.

This isn't a question of how to make the strongest joint, it is a question of has he made an adequate joint? I can't say absolutely. The majority of my destructive testing on joints has shown failure of the wood, not the glue joint.

 

[JEM]

I think your 9x factor may include the use of fiberglass over the fillet. But I'm not familiar with the publication you're referring to.

 

[oldsparkey]

Jeez Guy's...

All I know is the boats I have made with just the fillets and then total glass encapsulation of the boat works for me. So far I have not had to swim out of the Okefenokee Swamp or the Everglades while enjoying one of the boats on a trip.

If a person was not going to encapsulate the boat with the fiberglass then I would say that the glass taping of the seams would be a necessary item for the paddlers safety.
Unless they felt really lucky ... The question is... Do they feel lucky ? :lol:

Chuck.

 

[keith]

i think it is a pissing test. all people that build a boat are not boatbuilders and everyone that has a cad is not a designer. i build a looot of boats and dont ues any fillet or glass, but i use real wood and have stayed at holiday inns, what was the question? later keith

 

[Jimmy W]

I think your 9x factor may include the use of fiberglass over the fillet. But I'm not familiar with the publication you're referring to.

Seedtick did quote the publication that he is refering to up above.

Below is a picture that Nocatee posted of his punt. With a double layer of tape on the outside, chine logs in the center, and filets on the rest of the inside and probably glued and/or nailed to the frames, I think that it is unlikely that the bottom is going to come loose or leak.

edit: I just read his first post again, the bottom is also glued and nailed to the frames.

 

[JEM]

Seedtick did quote the publication that he is referring to up above.

I'm not doubting that it exists. I've just never read it or heard of it before. But there's lots of book that fall into that category.

double layer of tape on the outside, chine logs in the center, and filets on the rest of the inside and probably glued and/or nailed to the frames

It sounds pretty much bomb proof.

 

[JEM]

i think it is a pissing test. all people that build a boat are not boatbuilders and everyone that has a cad is not a designer. i build a looot of boats and dont ues any fillet or glass, but i use real wood and have stayed at holiday inns, what was the question? later keith

Call it whatever you want. Make vague insinuations or be man enough to say what you mean specifically and directly. Either way, it's only your opinion.

 

[oldsparkey]

GENTLEMEN...... I am using that term loosely in place of combatants. :lol: Let me offer some ideas.

1 ... Don't you all think it is time to go to your respective corners and take a break. Use the time to think about the different options or ideas ( opinions ) and then come out , shake hands and reach an mutual understanding. ( See Number 3 )

2.... After all both of you make beautiful boats and they are made two entirely different ways ... Just like the way Ford makes a truck compared to a Dodge or Chevrolet , if you get my drift. ( a hint here , not everyone does it the same way) :roll: ( See number 3)

3... Or just tell me to butt out , get lost , take a hike , go for a long walk off a short pier , feed the sharks by swimming with them do that dental work on the pissed off Gator with the tooth ache.
If you like this one ... then aim the aggression at me. I can take the heat , besides it would feel good in this cold snap we are having . :lol: :lol: :lol:

Chuck.
I realize this is the serious section ... but ... this might be getting (escalating ) to be to serious ... DAM , I never thought I would ever say that.

 

[tx river rat]

Seedtick and Kieth
I fully agree yall are the folks on building with all wood boats.
Now you get into welding thats my ball game 40 plus years a list of aws certifications as long as your arm.
A fillet on metal is normally two similar metals melted together with 100 percent penetration if don correctly you made 1 single piece from 2
Now on a wood fillet you have the wood , similar materials with there own stress factors and bending rates, and then you have the glue (fillet) it holds by surface adhesion not a 100 percent like metal and has a different rate of bending and stress factors than the wood.
In metal this would be like welding two pieces of cast iron with a ni rod
not to strong with out reinforcing
Your chine logs are a different ball game all are similar in there characteristics.
I should have worded my response differently so I will do it now, a fillet has several things it does some adhesion for strength, and for the glass to be layed in a way that it conforms to the curve of the fillet .
The joint will have a major increase in strength from glass tape being applied for several reason 1 is the tape covers a much wider area to bond to so distributes the forces applied to it over a much wider area
2 the addition of another layer increases the strength.
3 the tensile strenght of the glass also adds strength.
To sum this up for an inexperienced builder if you are going to wrap the inside and out with cloth and glass no tape is not necessary
Can you get by with just the fillet ,maybe depending on how well you apply mix it ,and how you use your boat and how good a craftsman you are
will the tape make a stronger more durable boat yes there is no doubt about it, it will be much stronger.
Ok I might not be a designer are boat builder but thats my 2 cents
Ron

 

[seedtick]

sorry Ron but I thought that welding codes did not take penetration into account on sizing fillet welds

"Currently, the AWS D1.1-98 Structural Welding Code –
Steel and the AASHTO/AWS D1.5-96 Bridge Welding
Code do not account for penetration when determining fillet
weld sizes." Some codes do allow for some penetration.

http://www.jflf.org/pdfs/papers/design_file3.pdf

No matter, I agree the fillet does make it stronger, more glass will make it stronger, they all act to spread the load - heck a two by four nailed onto the chine will make it stronger

The original question was does he NEED to add tape to the joint. Friend Keith and I have built dozens of boats with inside chines and no tape or fillet on the joint or fiberglass on the outside. We were trained by old time boat builders that built literally thousands of boats over their careers without epoxy or fiberglass.

So, does he NEED it? likely not

Can I guarantee that it's strong enough? Nope

Will extra this and extra that make it stronger? yep

I've said all I'm going to say on this subject, sorry if i said too much