STEM and STERN POST FILLETS

[marc]

Is there anyone who have a good and quick solution to make stem and stern post fillets for little Tiki or Hitia.

My process is as follow :

- make little fillet to glue the side

- cut the wires

- make the keel edge fillet and fill the wires holes at the outside. It is to avoid leaks during next steps.

- make a fillet to obtain a sort of tin along the post. 

- fill the tin with liquid epox just to be sure not to have void. 

- make a plastic mould for the upper part of the post and finish the fillets

 

3 or 4 days for all these tasks !!!

[paul anderson]

g,day mate well it just so happens that i have just epoxied the keel and stems on my tiki 26.your method is very thorough but i would and did leave the wires in until the glue had well and truly set.you can melt them by using a battery to short the wires,i have not done this but i have read a post about it somewhere.i have not completed the upper parts of the stems fillets but will do so after a quick sand,the first mix of epoxy for the keel i mixed to a runny ketchup and found this entered many of the hole drilled through the keel.when i flip the hull i will use a syringe to bung up the rest of the holes.cheers paul.

[ralf.henschkowski]

We did that in one go, but had to take extremely care that no bubbles formed in the fillet.
So during the curing we had to pierce some bubbles, fill with new filler, and form the fillet again and again.

The wires I removed several days after that. I heated them with a lighter and could then pull them out easily - one has to make sure that the ends are not too long and red hot, then pull steadily.
The holes were then filled using a syringe filled with epoxy (thickend with colloidal silica).

[Ricardo Aráoz]

Hi, not yet started (just recieved my study plans) but was amazed at the amounts of epoxy in that stem fillet. I would have glued some wood to the sides of the stem ply in order to use less epoxy, wood is cheaper.

Same thing with the rest of the fillets, if there is a lot of space to fill, why not put some wood in there and then finish the fillet with much less epoxy? I guess wood would be structurally sound, after all the rest of the structure is wood.

Any thoughts about this?

[Omar M. Rashash]

There are a number of places in the HItia 17 where epoxy is specified, rather than fitted wood parts, because it requires a lesser degree of woodworking and/or may be faster to do.  The sheer stringers on my Hitia 17 are 1-1/4" (31mm), rather than the specified 1" (25mm), because I prefer to plane a running bevel on the sheer.  This use much less epoxy when the deck is attached, but requires a higher level of skill to fit the deck.  Time wise it will actually be faster.  The bow and stern beg for some blocks of wood fitted and glued, rather than a mass of epoxy.

I don't see any point in removing the copper wire since the boat will be covered in glass, epoxy, and painted.  However, if you didn't use copper wire, or you were going with a clear finish, then removing the wire makes sense.  I have had situations where the copper wire wasn't doing the job and we needed to go with soft iron wire.  That wire MUST be removed.

[ralf.henschkowski]

I don't think you save a lot of epoxy. Most of it goes into coating the hulls and deck panels inside and out.

Besides that, IMHO the fillets (Hitia) are too small to add wood to it in some way.

Ricardo Aráoz said:

Hi, not yet started (just recieved my study plans) but was amazed at the amounts of epoxy in that stem fillet. I would have glued some wood to the sides of the stem ply in order to use less epoxy, wood is cheaper.

Same thing with the rest of the fillets, if there is a lot of space to fill, why not put some wood in there and then finish the fillet with much less epoxy? I guess wood would be structurally sound, after all the rest of the structure is wood.

Any thoughts about this?

[ralf.henschkowski]

The book "Devlin's Boat Building" mentions that the wire should not be left in the hull, "because the normal heating and cooling cycles of the boat may cause the wires to migrate to the surface, marring the finish".

It's also not that much more work than cutting the wires,  I found.

Omar M. Rashash said:

I don't see any point in removing the copper wire since the boat will be covered in glass, epoxy, and painted.  However, if you didn't use copper wire, or you were going with a clear finish, then removing the wire makes sense.  I have had situations where the copper wire wasn't doing the job and we needed to go with soft iron wire.  That wire MUST be removed.

[Omar M. Rashash]

Well, an author making an observation, without anything empirical to back it up, is simply stating an (unproven) hypothesis.  Chris Kulczycki, the founder of Chesapeake Light Craft, states in his book, "Stitch-and-Glue Boatbuilding, that- "Some builders claim that over time the wires can work loose and poke through the fiberglass.  I have never seen this happen."  I suspect he's got a larger sample size to draw on for his statement than that of Mr. Devlin.  Using Mr. Devlin's rational, staples would never be left in the hull either, during the construction of composite structures, yet they routinely are.

If the Gougeopn brothers (West Epoxy) were to make that statement, along with the supporting research, I might be willing to agree, but until then it's merely unsupported speculation.

[Ricardo Aráoz]

Probably so, but my question is : *IF* you decide to fit some wood instead of the epoxy in the fillets, would it be structurally safe?

Omar M. Rashash said:

There are a number of places in the HItia 17 where epoxy is specified, rather than fitted wood parts, because it requires a lesser degree of woodworking and/or may be faster to do.  

[Omar M. Rashash]

I can only speak to the HItia 17, since that's the only Wharram I've got plans in hand for.

I'd be very reluctant to make ANY changes to the specified filets in the hulls because I suspect they are doing more than just holding the parts together.  Just as in the crossbeams, they are a STRUCTURAL element of the design.  A laminated wood stem may be stronger than the existing design, with the heavy bow and stern fillets, but the amount of labor would be excessive compared to the possible weight savings and the amount of epoxy used would probably be the same.  Substitution of wood into areas that call for epoxy may produce results that are other than what the designer intended.

I guess another way to say this is you could reduce the size of the epoxy fillets, and the wood around the joint would still fail before the fillet did, but the smaller fillet would be more flexible, and therfore the hull would also flex.  Excessive flexibilty of the hull, beyond the design limits, could lead to catastrophic failure.  This may not be a big deal if the water temp is 70 degrees, and you're 800 yds. from shore, but if the water temp is 50 degrees, you could be dead within an hour.

[kim whitmyre]

The fillets that run from the aft stem along the keel area to the bow stem are exceedingly important to the integrity of the hull.  On the tiki 26, after the first fillet is applied a straight epoxy mix is applied beyond and over the fillet, and a piece of fiberglass tape is laid into the epoxy. Then a larger fillet is applied, and the process is repeated twice. So you have 3 layers of fiberglass tape imbedded into the fillets which makes the hull join very strong. I daresay much stronger than inserting dimensional lumber.

[kim whitmyre]

Your work looks excellent, Marc.