Another 25 Seafari goes under the knife

[Islandtrader]

For what its worth the 21 showed stress in those areas also. [img]/forum/images/graemlins/tongue.gif[/img]

[Blue_Heron]

While inspecting the stringers and tabbing, I discovered that the tabbing on the starboard side looks twice as thick as the port side, and extends farther down the hull bottom and farther up the side of the stringer. It looks like a QC glitch and the second layer of mat and roving got left off the port side. It’s probably not a coincidence that the tabbing on the port side was showing signs of delamination.





So I trimmed the port tabbing back to within about ¾” of the stringer and ground everything down to good fiberglass so I could tab the stringer more securely. The tabbing was pretty thin and wasn’t hard to peel off.





In addition to replacing the tabbing on the port stringer, I decided to add a bulkhead forward of where my water tank will go. The bulkhead will form the aft wall of a below deck storage compartment, and the forward wall of the water tank compartment. Because I took it from stringer to stringer, it should add a lot of stiffness to the forward sections of the lower hull panels. Here’s the bulkhead tacked in place and coated with thinned epoxy resin, ready to be glassed in.




And the port tabbing redone with four layers of 2408 biaxial and epoxy resin. Using epoxy resin may be overkill, but it makes a stronger laminate that will bend farther before breaking than polyester resin will. I only want to do this once, and the difference in cost between polyester resin and epoxy for this little structural adventure is less than $50. And using epoxy with a fast hardener allowed me to do this work at temperatures that were cooler than ideal for polyester resin.



That’s all for now. Gotta go finish my Christmas shopping. Merry Christmas, everyone!

Dave

[SBD]

Great post and great work!

I had a very similar tabbing failure on my boat. I used a grinder to trim back the delamination...it was awful job under the deck. Yours looks very tidy. How did you do it?

[DonV]

Gotta go finish my Christmas shopping. Merry Christmas, everyone!

Perfect!!!! Waiting until the very end!!!! A true CSC member holding up the male end of the "last minute shopper".

[strick]

Great post and great work!.it was awful job under the deck. Yours looks very tidy. How did you do it?

Dave must be very skinny to be able to get under there I've been under that area as well and to be able to do the work he accomplished is no small feat.

I've been trading e mails with both Dave and Conner about this. Sorry I have not got back to you guys sooner on this issue. I wanted to inspect both my boats before I made any comments on the subject.

The 25 that I just re did does not have any evidence of delamination on both the starboard and port stringers. The other 25 seafari that has been sitting is difficult to inspect the starboard stringer but I did not see evidence of delamination on the port side.

I can see from Daves pictures and from looking at both my boats, there seems to be some inconstancy in the way that these stringers were glassed to the hull. On the 25 that I just re did The woven roving that glasses the stringer to the hull extends about 10 inches down from the inboard side of the stringer onto the hull. On the outboard side of the stringer it extends another 8-10 inches and stops partly going up the side of the hull. On the 25 seafari that is sitting it is glassed the same on the inboard side however on the outboard side the glass extends significantly more up the side of the hull. On both boats the woven roving goes up the side of the stringer on both sides and over the top to overlap each other. In Daves pictures it looks like the glass only goes up half way on the side of the stringer.Both my boats were built in 1973. Here are a few pictures.

restored boat:









Un restored boat:





Another potential problem in any of these old boats is the forward bulkhead under the V-berth. In most of these older seacrafts they consist of 3/4 inch plywood tabbed to the hull. There is a drain hole in the bottom most part of the V and water can get to the exposed bare wood. Once this bulkhead begins to rot out it creates instability and can lead to flex. Below is Daves diagram were I've added an arrow pointing to the bulkhead.





happy seacrafting to all

[Blue_Heron]

...it was awful job under the deck.

You got that right, Sean. I spent about 4 hours under there with a belt sander. I've got a 4"x24", 8 amp Porter Cable and used 40 grit belts. If I'd tried to do it with my little POS Black and Decker belt sander, I'd still be under there. I turned the sander up on its nose so the front roller acted like a drum sander. I’ve found this method leaves a very coarse surface so the laminate can get a good mechanical bond.

To remove the old tabbing, I slid a wood chisel under the loose edge and then cut it loose at the fillet with this:



For laminating the tabbing, I wet out the biax on a sheet of visqueen on a workbench, then rolled it into a tube, climbed under the deck, and unrolled it into place. What a mess. I spent a good 20 minutes with a fiberglass roller rolling out the bubbles and wrinkles. There was quite a bit of cussing involved. The bulkhead was easier than the tabbing because of its smaller size and went pretty smoothly.

Dave

[Blue_Heron]

Dave must be very skinny to be able to get under there

But not skinny enough to do what came next.

I need to build a deck for the water tank to sit on. The deck I removed had no support underneath other than the floatation foam. I wanted to do something that would both support the tank deck and stiffen the hull. So I took some 4” extruded foam I got from a friend:



got out my ACME hot wire foam cutter…



…and after a little sanding to round off the corners, I had foam cores for my stringer/ deck supports.



It was at about this point, after considerable puzzling over how I was going to get under there to laminate the new stringers, that I decided to cut another hole in the deck. Given the amount of cussing involved in getting those stringers laminated, I’m pretty sure the effort would have failed completely if I’d tried to do it from underneath the cabin sole.

I put in a new partial bulkhead between the fuel tank compartment and the water tank compartment and then glued in the stringer cores with thickened epoxy and laminated and tabbed them with three layers of 2408. I still have to clean up the limber holes and a few rough spots on the tabbing, but all in all, I think it turned out ok. While I was at it, I reinforced the tabbing on the starboard stringer with three layers of 1808.



The hole I cut in the deck:



The forward hole will get a hatch like strick's. The larger hole will get closed back up. The balsa core is in good shape, so I'm just going to laminate the piece I cut out back in place once I'm done with the work below decks.

Well that pretty much brings us up to date. And I finished my Christmas shopping.

Merry Christmas,
Dave

[Blue_Heron]

Ok. A little more progress.

I put a bottom with a sump and drain in the forward compartment created by the new bulkhead. Before:



I used styrofoam to form the bottom and the sump. The foam just provides a flat surface for laying the glass. It is not structural and not a core.



And the compartment bottom after it’s glassed in:



I also glassed in the decks for the fuel tank and water tank compartments. Fuel tank compartment before:



And after:



Here’s the water tank compartment looking forward from the fuel tank compartment before the deck went in. The PVC pipe will go from the fresh water tank to the pump, which will be located in the engine compartment.



Here’s roughly the same view after the deck is in. I also put in a partial bulkhead at the midpoint of the water tank and a couple pieces of fiberglass angle that I fabricated and then laminated in place. These will hold the tank in place laterally.



Tomorrow, I will install my rigging tubes from the helm to the engine compartment. Once those are in, I can close up the deck over the water tank compartment.

Dave

[Blue_Heron]

I started patching the cabin deck over the water tank compartment. I ground the edges of the deck and the piece I cut out and suspended it in the hole with a couple strips of plywood.





Then I crawled under the deck and glassed the seams from underneath. What a job that was. The vertical space is about 9".





Tomorrow I'll glass the top of the seams.

Dave

[ScottM]

The vertical space is about 9".

Definitely not for the claustrophobic. Must have been pretty tight quarters in there.