How to trace and cut bulkheads

[ath]

Many of the bulkheads that I removed from my Cal 25 didn't come out as cleanly as I would have liked in large part because they were rotten and had been eaten by termites (photo). They came out in small pieces and I lost the original shape from which to trace a new bulkhead.

Interstingly, while doing this I also noticed that almost all of the woodwork, where it either attached to the deck or hull was not cut to fit so that gaps of one inch and more! were attached by glass. This gave the effect that that the plywood was floating. It wasn't surprising to see that much of the glass attaching the plywood to the hull had seperated. I found an old brochure that shows how the boats were built back in the day (see photo).

Cal 25 Keel

The above thread touched on this issue. When I removed the rotten floor board which was glassed in along the edges, I finally began to feel the keel swing the way most Cal 25 owners had talked about (a non issue apparently). The keel, as a seperate fixture, is not attached to the bottom of the hull like many boats. The curve of the hull continues down on each side forming the keel and at the very bottom of the bilge the lead ballast is attached by bolts. Again, inside the cavity,which is the bilge, inadequately small pieces of plywood were glassed in crossways. Most of it was seperated providing no strength at all (see photo). So, unless the floor board is securely glassed to the hull and securely fitted to these cross pieces inside the bilge, the keel will sway port/starboard.

In addition to wanting to replace old bulheads, I would like to reconfigure my interiror and beef up the structure of the boat for longer cruises. I'm thinking of possibly putting in water tight bulkheads fore and aft for example. (I've recently developed a fear of sinking that I never had before - too much Discovery Channel). But I would like to cut pieces that I almost have to wedge into place for being such a tight fit.

Having nothing to use to trace with, what is the best way to capture the most accuate template to cut a bulkhead? One piece, I imagine, might span the entire beam from deck to hull. Is there a tried and true way of capturing the exact curves in the hull and deck to lay over a piece of marine ply?

Thanks again in advance for the expertise provided in this forum.

[stevel]

The reason that the bulkheads are cut with a gap between their edges and the hull is to avoid creating a hard spot on the hull, which would then result in gelcoat cracking, and eventually in catastrophic panel failure.

The projects that you are taking on with your Cal 25' are thouroughly covered in the book, "This Old Boat" by Don Casey. (The Amazon URL is http://www.amazon.com/exec/obidos/tg/detail/-/0071579931/qid=1117638132/sr=8-1/ref=pd_csp_1/002-6619389-2582424?v=glance&s=books&n=507846 ). I'd also check out the articles on David Pascoe's website ( http://www.yachtsurvey.com/ ). Both resources are in layman's terms, and Casey's humor is refreshing.

[ath]

Thanks. I'm glad I checked before continuing. I'll take a look.

[Tim B]

From that and the state of the keel I'd be very worried, if the hull skin is thick enough then panel failure shouldn't be a problem. if it isn't well....
One solution to the problem would be to build the new bulk-heads from foam and glass. advantageously, you can rough-fit the foam to the hull then use expanding cavity wall foam to fill gaps. Glass over the outside and this should give a structural bulk-head that has just enough flex in it to prevent the gel-coat cracking.

As far as the keel goes, I can only suggest that you build a few internal beams (attached to the floor to spread the load) and do your best to re-inforce it. if you do much more to it, you'll just end up re-building it.

Looks like a nasty job,

Tim B.

[ath]

Tim,

It's actually not as bad as it looks. I've done a lot of research on the keel and apparently it's been known and talked about since the boat was first launched. There are many fleets still racing around the country and few have done aything about reinforcing the keel. However, your suggestions is worth looking at as I would prefer to be safe.

I took her out a few times and she performed exceptionally well in 8 - 12 knts. I only have a 150 Gen so in 15 knts+ she began to heel past 20 and slide a little. But well balanced, responsive, tight and quick after all these years.

I'm one week into it (photo). A lot of grinding and eating dust but I'm having a good time. Back to work.

Thanks again for all the group's wisdom

[ebb]

Hey 'ath',
There's good guys looking in here!
And you got a thorny problem getting the lead keel secure. You probably have someone in your class that's done it. But you have to deconstruct the junk ply grid, supporting the ballast outside, of course. Then you can add new non-rotting floors back (without any spaces along the hull) and epoxy the hell out of it with 100% solids 2part laminating epoxy and xmat.

Check out Casey on your keel bolts. There are signs that will tell you what your problems are. For instance if the 'bolts' have resin encapsulating them they are probably s.s. They may be stud bolts that were cast into the lead. You best restoration is to drop the ballast and rebed it. Anyway you got to find out what the keel is held on with. And what to! Once the cavity is forensicly cleaned out, ie carefully, then it's probably easy to permanently keep plywood out of there and beef it up with epoxy. Would not put any urethane foam in the bilge.

On the larger bulkheads, you'll find somewhere the story stick method of making a pattern. But I make patterns with posterboard, actually 'card' material I get at Staples. It's a little smaller than 2'x3'. You can take up a single sheet and just begin pressing it into the shape you want, against the hull, along a rotten bulkhead whatever. Thumbnail is acurate enough. Cut it along the crease you made then detail the pattern with strip and pieces stuck on with blue tape. Not elegant, but fast. I often cut a doorskin 'pattern' using the cardboard one on important pieces. Dustless if you use a utility knife.

Cut the new bulkheads allowing for a piece of 1/2" peel-and-stick foam along the hull edge. You get a nice fit that way. Then you fillet and tab. This is useful and important on major bulkheads in engineered boats with thin hulls as the tabbing will add tremendous strength to the hull.

[mattotoole]

Many of the bulkheads that I removed from my Cal 25 didn't come out as cleanly as I would have liked in large part because they were rotten and had been eaten by termites (photo). They came out in small pieces and I lost the original shape from which to trace a new bulkhead.

I've always used the batten method, a bunch of them cris-crossed until I have enough end points to trace a new bulkhead. Hold the first few in with duct tape or a glue gun, then wire them together at the junctions. It's sturdier and more accurate than cardboard. If you want to get fancy you can interleave them so the ends are roughly in the same plane.

[ath]

Great stuff! Fortunatley for me, I have a small boat = small bulkheads and so either of these methods should do the job. Thank you.

As for the keel, I don't see that I have a problem. I didn't have any sway at all until I removed the floor board. The through bolts are clean. The underside epoxy shows no wear.

Also, I have not read or heard of one report from any owner or fleet where the keel has broken loose in the history of the Cal 25, whereas, I 've read of numerous other boats that have lost keels, snapped off at the hull where they were through bolted, shearing the bolts (Open 60's for example but in the most extreme conditions/didn't Conner's America's Cup boat also lose a keel in trials off San Diego?).

Perhaps there is something to be said of the design after 40 years of racing and cruising (one guy sailed a family of five around the world in a Cal 25 - book "Into the Light" and remember the "Dove" - a Lapworth '24) and a very large number of the boats surviving. Many disconcerted owners have complained of the unsettling motion of the keel but few have done anything about it and eventually grew accustomed to it. My natural inclination is to beef up the keel and floor board with epoxy as suggested. It just seems to me that forward energy is lost and disipated through the bending. However, one member put it this way ...

Quote: "Tread very carefully here! This is a place where you could make a problem by causing point loading of the structure. Many people equate deformation with high loads, but this is not the case. Like a fishing rod, many structures are designed to bend, not break. In bending, they spread out the load along the length of the structure which lowers the overall load on any one portion of the structure. In this case, deformation energy in an unstiffened composite structure flows in the outer skins. Adding a stiffener to prevent deformation prevents energy dissipation and increases the load at the rigid point. An analogy is slipping a short heavy steel tube over a fishing rod, the rod brakes at the intersection of the tube and the glass.

Because yours and other class hulls have survived so long without problems, I think this "wiggling" is the effect of a conscious design decision. Without doing a complete structural and layup analysis to ensure proper load pathing, adding stiffening seems like a bad idea in my opinion." end quote.

So maybe Bill Lapworth, consciously or unconsciously, came up with a proven design. Isn't a good rule of thumb the "test of time"? I leave it to you, the experts.

[grampianman]

Hello Ath,
I'm repairing a 30 year old Grampian 23 and have repaired one of the main bulkheads. I use a long metal rod (6 feet X 1/8" dia) to get the curve of the hull then transcribe onto the 3/4" ply I am cutting. This is how I have seen shipwrights get the curves for cutting wooden floors and timbers for wooden boats. I have a site on tripod which also shows the deck recoring and the on-going repair to the boat. I must admit, I have encountered many things, but not termites!

Something else, I have used plywood for the bulkheads and various pieces of furniture, but when it came to the floors in the bilge, I used solid pressure treated lumber. I prefer a single piece of wood in an area which could be regularly encountering water, especially fresh water. I also mix up an epoxy paste which I slather on prior to placing either my bulkheads or the floors.

Good luck with your repairs.

[ath]

Yes. The solid piece of wood does make sense. The boat is dry now but that is an area that could get wet. Can you expalin more how the rod works? Does it bend?

[astevo]

make yourself a profile gauge,
get a piece of timber and drill holes through it ever 50mm along its length, in these holes put a piece of dowel which is friction fit in the timber, then put the timber down and slide the dowel down to the surface, to copy the curves.

[yokebutt]

Ath,
One simple way to template a bulkhead is to suspend a good sized piece of plywood in the location where you want to put the b-head, then you hot-melt glue a bunch of free mixing-sticks from the paintstore to the plywood with one end of the stick touching the hull, or you can use a jiggle-stick and mark its positions on the plywood. Once you have enough points marked you just lay the plywood onto the b-head material and transfer them, then use a flexible batten to connect the points into a line.

Good luck,
Yokebutt.

[ath]

Thanks again.

[WildCherry]

I did a few diff methods of traceing mine out. I measured them every 6 inchs so I had a number to use as a refernce. I also Had thick paper that I taped up and laid out on top of them , that I was able to trace an outline. I then cut my paper out and measured it to see how close I was. I was closer with the paper outlines than I thought I would be. I traced and cut. It allways takes a little adjusting to get it to fit right.

[ath]

Paper seems easier to get in and out of a smaller boat. I'm still ripping things out and grinding, so I am not yet to the point of cutting new bulkheads. I must have removed 500lbs or more of wood and other things. The boat is now sitting 6" above the old waterline.

I removed all of the plywood trim, which I think is useless since it conceals potential and ongoing problems, only to discover more rot. It is the deck this time where rails had not been properly caulked. They don't look like hand rails. Ironically, I think they were installed to deflect water away from the cabin hatch (another story). It looks like they've been leaking for years. And the chain plates have leaked and were attacked by termites which means I'll also have to replace the mast support. Strangely, the deck has never shown any sign of weakness - sponginess, flex, etc. Even now when I tap it with the back of a srewdriver, it resonates like a guitar sounding board.

Looking forward, the pulpit had been leaking too and now I'm worried that the forward deck might be delaminating - although from on top and underneath there are no signs at all (except around where the stantions were). I hesitate to bore into the deck too look.

Is there some other way I can know for sure if that part of the deck good or not? (any new pictures of Wild Cherry)