A detail of the cracked glass tabbing and lack of bond after I pulled the 2x4.

Going to Merton's for foam and resin soon.

That fuel tank hatch cover is going to lose 15 lb, I swear.

Any opinions on this tabbing? It looks original.
Also, Strick is right about gel coating the bilge. It holds up better than bilge paint.

It has been -1 here at night lately. I glued up some 1/2" H80 divinycell to make a 1" x 6" "hat channel" to replace that rancid 2x4, and better allow me to fit fuel tank fittings. If the old epoxy kicked (the wood stove is going), then I can rip chamfers to make it a trapezoid shape so I can lay glass on it. Cold west system epoxy doesn't pump very well. I bet the 5 gallon jug of resin was 45F...

I don't care for epoxy, but in this case, it will work. It won't need gel coat, and I can use it indoors in winter next to a wood stove without blowing myself up or stinking the house up.

I have been thinking about cockpit drains. Strick had some advice a while back that I kind of ignored, and now I am going to listen to it. Or try to.

Anyway, at home depot today I found a brass shower drain with removable stainless screen plate. $22. A PVC version was $11.

It looks perfect for putting in a sandwich cored deck with some 5200 sealant.

Thoughts?

That tabbing in the previous post does look a little on the light side. It would not hurt to reinforce that.

I don't remember which previous advice your talking about but my advice on the above post would be to use marine grade deck drains from a marine mfg. I would think that they may hold up better. I'm sure you could find something similar. She is looking good.

strick

Construction of the under deck brace to allow the tank to fit. This will be shallower in cross section, but more glass, and foam filled. (Obviously).

I had to laminate two strips of Divinycell H80 to get 1" thickness (I didn't need a whole sheet of 1"). So that is West System in the joint making it look like a jam sandwich. I really don't like that stuff, I get rashy when I use it. But I couldn't lay up vinylester in the basement.

The offcut from making the trapezoid makes for a nice foam fillet- that's a plus.

So I looked for cockpit drains- there is a similar shape Marelon drain in 1-1/2" diameter for about $30. The chamfer on the flange is a lot steeper. Not sure I like that. But it won't corrode.

I de-cored the fuel tank hatch today. Probably 15 lbs of soggy plywood in there. That will be getting the divinycel treatment, too. Between that and the wet 2x4 "supporting" the deck, I bet that's a 25lb weight loss.

Well you could always pull them out if they corrode and replace them with the Marelon but then you would be doing it twice :) I'm doing something twice right now and I'm missing out on the spring striped bass run.....

strick

Agree with strick on the tabbing. I'm assuming you have checked the lower portions of the bulkheads for rot.

Just a general comment. I sure no expert on boat construction, but have spent a modest amount of time rummaging around the the guts of Bertrams, Seabirds and several older 20ft seacrafts, and it seems to me that the construction of the 25, particularly mine, is pretty sloppy in comparison. Yours looks in the same range. The design is wonderful, but I'd beef up connection points, like the tabbing, and make sure the stringer tabbing forward is still tightly stuck.

I haven't been in the bilges of enough 20-25 foot glass boats to speak to this, but that was my impression. Without really thinking about the boat as a whole structurally, just the parts I can easily see, and do math on, I purchased 1/2" and 3/4" divinycel H80. So the tank decks will be structural with 1/2" H80 and glass to support a poly tank or two. I will likely run a layer of 1708 up to the stringers to reinforce that tabbing. The under cockpit sole bulkheead will be doubled with 3/4" H80 sandwich core (and glass). I will leave the plywood in place, partly to hold hull shape while I put in the sandwich core bulkhead doubler but likely will remove the bottom 4-6" as it got wet once. Then I can remove the ply at my leisure. Then I hope to put a deck forward of there out of 1/2" sandwich core again to better support the area where the slamming loads are higher. Until I can fit another bulkhead under the vee berth.

The tank deck will be glassed/ tabbed to the hull on the top surface, and tacked to the keelson with 5200 adhesive. Or that's my plan.

Oh yeah, the bulkhead from the tanks to the engine bay need replacing, too.

I like sanding...

Oh yeah, in the plus column, I got the electronics bench wired today. Radar, structure scan, GPS. And sanded the radar mount for one more layer of gel coat.

It SNOWED yesterday. Can you say cabin fever?

before you start working on the tank supports, pull that bulk head. Such a joy, you will really have a good time. In mine the small stringers that support the tank go through the bulkhead and end in a mess, just beyond it. You may have to redo those stringers.

I think I posted pics of my short stringers in your "odd crack on a 25 seafari" thread. I think they are ok. I think, I think.

I am terrified of pulling that bulkhead and hooking the hull, so I think I have to stick with doubling it, then removing the ply from the hatch in the cockpit sole, then finishing the tabbing. That just means I won't bond the sandwich core panel to the existing ply bulkhead. I think.

I will probably leave both bulkheads in when i run this summer, and finish pulling the ply bulkhead in the fall. Otherwise I will be too far behind before vacation.

Know what you mean. I was one very happy(and relieved) man when mine went back together with no glitches after I was forced to remove all of the bulkheads with one very bad stringer.

Your strategy should work, but it is going to be one hell of a painful trip to remove that bulkhead without being able to get all the way under the deck. I cut a big access in the cabin sole almost back to the forward tank bulkhead. That way I could get all the way in the hole, which was bad enough.

I think your concerns are unfounded. If you support the keel at the transom and forward of the CG, as long as the deck is intact I don't think you need to worry about introducing a hook. The outer hull is very stiff, and the stringers and keel provide plenty of longitudinal stiffness. I removed most of that bulkhead below the deck and had no issues.

Dave

I think Dave is right. The main stringers are massive. I had no trouble, but the keel was very well supported.

Things to consider: Does the trailer it sits on give the keel good support over a big area? Is the keelson rotted out. i.e. just a fiberglass shell? Are the rest of the structural pieces intact and well stuck together, bulkheads, deck, stringers, tabbing?

If all that is good, I wouldn't worry about it.

I spent Saturday hunched over the fuel tank hatch with a belt sander removing the sins of prior repairpersons unknown.

Sunday I siphoned maybe 30 gallons off the tarp on the bow of the 25. Coiling up the garden hose, I stood up and threw my back out. Of all the damn things. Discs are ok, but holy cow, the past 72 hours have been uncomfortable. Even with muscle relaxers and decent level pain meds. Sanding fiberglass is a young man's game.

Fish,
I feel your pain: I just make it look easy: NO BACK STRAINS, or I'll pay: I keep Advil in all of my environments-

It appears that my tank support stringers end right at the bulkhead of interest (under the cockpit sole). So that will be easier. My tank deck will be lower than those- just about touching the keelson with the 1/2" H80 sandwich core.

Ultimately once I get the under cockpit bulkhead sorted, I think in 2015, I will extend a tank deck like surface above the keelson forward to the next bulkhead in lieu of addition of another proper bulkhead.

With a thrown out back, I won't do much this weekend but send props out for a tune-up, maybe. And I will hire some help for trailer mods and sanding the planing surface dead true. I have a goal of 50MPH, if not 50 knots. If chine walk doesn't get me first. But I need low, low slip numbers to get there. 3-4% Even with a bravo 3, it probably won't happen, but it is nice to dream.

If you hit 50 mph with a 350 Mag MPI and a Bravo III, I'm gonna go out and buy a Bravo III. I wish you luck, but I just don't think you'll get there. 25° deadrise = lots of wetted area = drag. But the faster you go, the more it will lift and reduce wetted area, so it's worth a try.

It is a nice dream. I will try- I did a *little* prop design once, so I have some concept of things to try. But I think low 40s is more realistic.

Worked on the tank hatch cover as much as my back would allow today.

For you Floridians- they call that white crap "snow". :D

Hatch is done. LONG story. I found out that you can "B stage" vinylester (stop and restart cure with temperature), and that you can dry out 1708 with just peel ply, a LITTLE pressure and a week long cure.

I was glassing and the temp and humidity was rising. So I kept dropping the hardener. The last layer, I diluted the resin with ~10% styrene monomer and dropped the MEKP to the slowest cure (5cc/ qt). Then the ambient temp crashed and the humidity skyrocketed. The temperature dropped to 55F in 18 hours in my workspace, and over the week dropped below freezing. After a week I had resin that was between tacky and genuinely wet.

But Joe Merton mentioned that the vinylester will cure in sunlight to a degree, so I decided to finish the part in a solar oven consisting of two layers of poly drop cloth. I threw it on the back lawn. The UV and heat restarted the cure, and I wet out the slightly dry cloth with a bit more resin. Final cure/postcure temp was probably 140F. It was a learning experience where it was harder to work with the mat than the 1708.

Something unexpected- 1-1/2 oz mat is stiff until resin gets to it, so getting it in corners was actually harder than the 1708, at least in this case.

Also, no guarantees on resin strength, but that hatch probably has 2 layers of mat and 2 layers of 1708 topside, and half that on the under (bilge facing) side. It sure is stiff and kind of rings when you tap it. I am happy enough as a learning experience with the foam. Which was the easy part, this time.

A lot of the time when it is cold outside and I cant do the work in my heated shop I will pre-heat the area with a hair dryer/heat gun and then once everything is laid I will heat the lambent slightly and once it starts to kick I found that the reaction of the vinyl-ester will produce enough heat to finish out the cure at its own natural rate. That's using 1%-3% mek. I don't like adding extra mek due to it getting brittle. But like you said a lot of the time the sun will provide all the heat you need to get it going. When I did my swim platform I laid it up in the shade and then carried the mold out into the sun to help it kick and soon as the sun started warming it started to cure out at a normal pace. Also sometimes I will turn the a/c on and cool off the shop to do all my lay ups and once Im finished I will switch to heat and bring it up to 85 degrees or so. That buys me more time to lay up everything and then get a good cure. I even cool the resin outside in thee cold and bring down the temp of it too but it gets thicker when I do that and makes it harder to absorb in to thick layers.

Halfway thru.

Did I mention that my workspace is a rolled up tarp in a borrowed shed? Still waiting on my laminating table, A/C and compressor. Or electricity.

down to brass tacks
 

I used 4 mil poly to trace the existing bulkheads. These are rough oversize cuts in 3/4" H80 divinycel. I need to trim at least 3/4" all around for the trapezoidal spacer. I hope to glass them this weekend. And maybe glass them in place next week.

I am going to pull the under cockpit bulkhead first, despite my worries about hooking the hull.

I will try to put CSM on both sides simultaneously, fiberglass (raptor) stapled down, let that kick, then lay down the 1708.

And yes, those ARE brass tacks.

I laminated the bulkheads this weekend. One with 1.5 oz CSM, then 2 layers of biax. The other with 2 layers of 1708 double bias (stitch)mat.

I did the latter all at once. Slow vinylester layup. 0.7% MEKP and 60F outside. I used peel ply, then covered with 2 mil polyethylene sheet. Then I flipped it and did the other side. That worked pretty well. The first one with the separate inner layer of 1.5 oz CSM isn't quote as pretty, and at 65F and 1.2% MEKP warped a little. Oh well.

If I did it one more time, I would use one inner layer of 1708DBM, an outer of biax (no mat). Pretty happy with the results. The 1708DBM panel is pretty light and very stiff, and I hope strong. The first with the separate mat is a little heavy.

The bulkheads still have peel ply on them and need trimming to final size, but they are WAY WAY stiffer than equivalent thickness ply. And lighter. Totally worth the work. I finished the under deck stiffener tonight, too. More pictures this weekend.

No turning back now!
 

Demoing the under cockpit bulkhead. That was a lot of work! I wish I hadn't repaired the tabbing last year with vinylester. It would have come out a lot easier that way. More grinding tomorrow, then sandblasting, then trimming the foamcore bulkhead to fit, then maybe fiberglassing, if time permits.

$58 harbor freight sandblaster with pressure feed. Going to take off a few layers of paint and gel coat in the corners of the hull before I glass everything in.

I hate grinding. I think I spent 5-6 hours with a 4-1/2 inch angle grinder with 40 grit flap wheel. And I got something (fiberglass, of course) in my eye, despite the glasses and the moon suit. Looks like nothing major, thankfully. And I look like I went to a paintball gun fight wearing nothing but jeans and a t-shirt. Little circular bruises everywhere. Laying on stringers all weekend will do that to you. :eek:

I slipped with the angle grinder and went thru the tabbing into the first layer of woven roving on a stringer. Nothing big, but I will patch it up. Thankfully, the stringer tabbing looks ok. I think this boat was a trailer queen, and damage is from storage, not flying off waves.

Then I grit blasted some. That is very effective. But I had to level out the surfaces for the foam spacers first. What a PITA. But it looks good now.

I also got the carbon fiber deck stiffener laid up. I managed to put a 3/16" crown in it (the right way!) for better deck runoff.

I may add one more bulkhead forward- or at least prep while I am in there- maybe CF over foam, as I forgot I has so much cloth laying around. Then I have to hustle to get this done before July 4.

I'm curious how effective the blasting deal is from HF? Was thinking about getting one of those for a project coming up soon.

Also, how the carbon fiber works for stiffening. I've been playing around with cloth/epoxy on a scrap piece of 1/2" Coosa to see how stiff it gets when laminating both sides. It does work pretty well but I think carbon fiber might be a good way to go despite the extra expense.

The boat looks like it's coming along great!

I got the small one. If I wasn't throwing it over a gunwale 6 feet off the ground, I would rather have gotten a large one for extra capacity. And get black beauty somewhere a lot cheaper than there. Like $0.25/lb, not $1 a lb.

Once I adjusted the media flow down, it worked great.

The carbon is stiff, and lighter than glass. But for what I am doing, I could have purchased a better glass orientation. (My 20 year old carbon cloth was free to me). I had a first layer of 1708DBM. So the fibers are at +/-45 degrees. Then two light layers of carbon in a 2x2 weave (I think), having a lot of roving running longitudinally along the stiffener- the most advantageous orientation for me. So it is quite effective. And light. But 1708DBM, then uni glass, then a biax cap would be pretty good, I imagine. Not quite as stiff or light, but way cheaper if I had to buy reinforcement. Again, I got my carbon for free, so that's why I used it there.

There are galvanic issues with carbon, so I only put it places where I won't screw into it. I believe it eats aluminum for lunch- worse than stainless.

And for the doubters in the bunch- the vinylester/ biax I put in last year was a LOT harder to remove and far more impact resistant than the original poly/glass. I was trying to break tabbing with a 4 lb hammer and getting nowhere on the vinylester. The polyester and glass broke pretty easily. It seems vinylester(epoxy) really does have a lot of elongation like ordinary epoxy.

I didn't know about the galvanic issues with carbon fiber. It looks like people do use stainless fasteners so I wonder what the longevity is. If it's a 10 year thing rather than say 5, I can live with that. My plan was to do one layer of fiber cloth and then regular glass over that. Same on both sides so point of contact would be minimal between fasteners and carbon cloth. I know where the deck fasteners will be so could just do a cutout in those areas to be safe!

Nice Job, FishStretcher. Your pics of the bulkheads coming out bring back a bunch of "less than pleasant" memories. I can feel your pain. Great that the tabbing looks ok.

Where do you plan to put your extra bulkhead? It needs one for sure forward of the forward tank bulkhead.

Connor

Practicality and timing will dictate this to a degree, but I intend to put it forward of the forward tank/cockpit sole bulkhead. If I have the time, I hope to put the foam trapezoids in after I gritblast a clean spot. I might lay a layer of 1708 over them with peel ply and leave the peel ply. If I get a bulkhead cut out in time, I will install it, else I leave the peel down. It will likely be in an area that I can reach from the two false bottom lockers under the bunks. Reach from both sides for installing the tabbing. One false bottom is yet to be created. The port side exists.

That way I can install and tab at my leisure. At least with respect to schedule, if not comfort.

It will be a low half bulkhead, not all the way to the cabin floor, I think. (I haven't measured yet.) But enough to keep the stringers from collapsing inward from slamming loads. I hope.

It is more of an issue with aluminum, as far as I know. But in a saltwater environment, it looks like even stainless will have a hard time?

http://en.wikipedia.org/wiki/Galvanic_series
http://en.wikipedia.org/wiki/Galvanic_corrosion

"Hard points" are often epoxy encapsulated for this reason on graphite composite structures. Kind of a PITA.

Cutouts in the cloth is one way to do it, I suppose. Or potting the joint so there isn't contact?

Clarity is good. Are there any concerns with the differing flexural characteristics of CF and glass?

The stiffness of the CF means that it takes the stress much faster than the glass for a given load. Plus the fiber orientation means it would do that, too. The biax will help spread the load well across the flange and into the bottom skin of the deck. I think.

The 4-5% elongation of the vinylester epoxy matches the glass well. The carbon will break long before that. But that's fine. If I ever get that far, then I will have a springy deck with broken CF, but likely some intact biax for a little while. I suspect that would be coming off a heck of a wave and slamming with a giant BFT on the deck. :D The CF isn't really lots stronger than the glass, but lots stiffer, and lighter, so it is very efficient.

I really want to put a layer of biax/vinylester in the hull between the stringers, but I don't have the time or resin. That stuff is so tough, it would be a great as a last line of defense against punching thru the hull. Oh well.

I think I am done grinding. And sandblasting. Sandblasting is great. It doesn't flatten anything out, but it roughs it up instantly. I went through 160lb of coal slag (black beauty) today. I think I spent 90 minutes vacuuming out the hull, though. This is really slow going.