DS1 Hull Stringers

[MarcCram]

Yes another long post from myself, I apologize in advance for asking so much.

I'm going to break this down into parts, all pertaining to the hull stringer repair, whats wrong, filler (wood or closed cell foam), maintaining correct hull shape.

Whats wrong... The hull has damage, the previous-previous owner did a very poor repair job and it has failed. Add to that, there are two cracks in the hull. I noticed when I first purchased her that one stringer had damage and suspected it to be damp. Turns out the entire piece is rotted, it looks like both sides are rotted beyond repair causing the hull to be soft. I've decided, since the rest of the boat is being repaired/restored to new that this has to be done.
Hull Damage, first a wide shot and port and starboard cracks respectively.


Using a Dremel and their new metal cutting wheels (they hardly wear even after cutting stainless) I removed the top part of the stringer.


I wasn't prepared for what I saw after I removed the rot had turned the wood into pretty much soggy cardboard, and it was all still soaked, even after sitting indoors for over a month with excellent ventilation.

The length is ~110", measuring the "driest" piece I get 2" wide and 3/8" thick. What I don't know is does the type of hardwood matter? What type of wood was used, I can't tell by looking at the pieces in front of me? There is a post here http://forum.daysailer.org/forum/viewtopic.php?t=543 that mentions foam core being used, I suspect the wood was initially used as a filler/gapper so the fiberglass could be laid on top of it.
Has anyone replaced re-glassed them? (I'm not a noob at fiberglass work)

Finally,
The boat is sitting on the trailer but I suspect this isn't the best way to support the hull and keep it in her correct shape. Has anyone built a cradle or other type of sling? I was going to try and build a 4x4 sling and support her using four 2" straps one at the bow, transom, and fore and aft of the centerboard trunk.

Thanks!
Marc

If you skipped most of the post, what type of wood (or closed cell foam) to use, and what is the best way to support the hull during this process.
pheww.....

[Thomas P. Bews]

As for the stringer that is rotted out. The wood was originally balsa. I had to make repairs on a rotted stringer on a DSI I owned a while back. The way I made that repair was to remove the entire stringer with a scaper/chisel and then sand the rough edges down to get good clean fiberglass so new glass would make a good bond. I bought a 2-2 1/2" PVC pipe which I cut into thirds lengthwise. The piece you want to use in cross section looks like a crescent. Cut this crescent piece to match the length of the original stringer. Lay the PVC piece in to the hull with the concave side(hollow side) down against the hull, then fiberglass it in place using a good quality woven fiberglass cloth. You may want to do several layers to give more strength and stiffening to the hull. Note: leave the ends of the stringer open so air can circulate under the stringer. Doing this will insure that any water that gets in there has a chance to get out. Sand the repair down to your satisfaction cosmetically and then paint it to match the interior color. The repair looks professional and will never have to be done again because the wood was eliminated. Good luck.

Tom

[MarcCram]

Thomas,
Thanks for the suggestion, I'm going to give it a try this week.

Doing the math cutting it into thirds makes more sense then cutting it in half. Since the original stringers were 2" wide and 1/2" high, using 2" PVC cut in half will yield a 1" rise, much greater then the original, also too high for floorboards. So triangulating (now in thirds) the PVC makes a circumscribed circle in which lies a equilateral triangle in which each side is 2". Using the law of sines we get 2"/sin60 (since each angle in a equilateral triangle is 60 degrees) = 2.31" or roughly 2 5/16". Taking in to account that a table saw blade has a width of 1/8" a 2 1/2" PVC pipe is the perfect, the rise is a little more then a 1/2".

I'm just backing up Thomas P. Bews in the 2 1/2" pipe selection.

Cheers!
Marc Cram

[calden]

Nice suggestion about using PVC to make stiffening stringers.

Reading all this makes me think I don't have any stringers in my boat. Too lazy right now to trek out to the garage. Can someone tell me where they would be exactly? Midway between the seat and the centerboard trunk?

Thanks,
Carlos

[MarcCram]

Hi Carlos
Here is a really dirty picture of my hull stringers, taken the day I brought the boat home.

They measure 110" in length, the balsa wood (thanks for the wood type in the previous post), is 1/2" thick and 2" wide.

I'm not sure if a second set of stringers were used right where the seats meet the hull. I don't want to cut my hull up anymore.

Hope this helps.

Marc

[Wyatt]

Hi Mark:

I'm up in Washington, Warren County, NJ and also have an older DS1 with hull problems. Your info on the stringers is interesting, and I may replace mine based on what you've found.

Anyhow, my boat also showed sagging, flexing, and one puncture on the port side. So last October I flipped it upside down in the garage and stripped all of the paint off, discovered that the gelcoat was seriously blistered and took a grinder to the entire hull.

What I found was that in addition to the puncture, the hull had stress cracks along the line where the seats meet the hull-- both sides. Those aren't stringers at the seat joint. The raised profile you see there is the flange on the seat assembly, which was apparently pre-fabbed and then glassed in to the hull. After many years of flexing, the joint at the seat flange/hull began to fail. Also, water and dirt had worked themselves under the flange inside the seat (the buoyancy chamber), further weakening the joint.

I am about to reglass the entire hull below the waterline, and install additional layers over the weakest areas (underneath the seats, which also happens to be the flattest portion of the hull). Then I plan on refairing the hull, and (hopefully) re-gelcoating. I'm going to use vinyl ester resin, not epoxy. It's cheaper, easier to work with, is compatible with gelcoat, and easier to sand.

Then I'm going to reinforce the seat-hull joint on the inside and take a look at those stringers.

Regards,

Wyatt

[MarcCram]

Wyatt-
That would be the Washington, NJ that Route 31 runs through? I drive through Washington on my way to the Poconos (its fast for me to take the North East Extension of the PA turnpike, but it's a much more relaxing and scenic drive the rt 31-46-80 way). Thats also near Brass Castle correct?
Anyway I hope to have the boat ready this season (even if its the end of the season) to head up to Lake Wallenpaupack in the Pocono's. And if so, I'll be passing through Washington on my way up (with a stop at Hot Dog Johnny's in Buttzville) along the way.

Sorry to hear about the blisters, my parents boat had that when they bought it when I was a kid and all I remember seeing the hull getting sandblasted (although stripping paint on a 40 foot boat is much more time consuming then our Day Sailers). What did you use to grind the paint off? I used a 6" dual action sander - hooked to a 25 gallon craftsman pro compressor, which barely was able to keep up. I used 40 grit (yeah 40 grit) sandpaper, keeping the disc flat the whole time was crucial to not digging into the gelcoat. I went through at least 5 or 6 sandpaper discs, they lost their bite really quickly, even at low speeds.

Thanks for the seat info, I have a damp spot on the starboard side at the aft section of the seat (at the flange), I'm going to have to install inspection ports (which the dremel's circle cutting tool should come in handy here) and remove/replace whatever is damp and rotted.

I had my wife take some pictures, I was too dirty to break out the camera doing work.



The majority of the damage is along the centerline of the hull, the centerboard trunk "flange" and where the transom meets the hull.

Good luck with the hull, let me know how you make out.
Marc

[Curry]

Hi Marc,

I too recently bought a DS 1, sail number 3157. The title identifies it as a 1968, which look about right for the number. My plan is to get it into the water this year and see what needs to be done to the boat to bring it back into condition.

My question relates to your nice clean hull. Is the water line I see in your pictures in the gell coat? And did the sanding bring it to the surface or was it part of the years of painting?

My boat has been painted (both topsides and bottom) many - many times and there is no line visable. I'd like to sand it down over this fall and winter and redo.

I'll get some pictures posted once I get the cover off of it in the next week or two.

Thanks,
Chris

[MarcCram]

Hi Chris,
Yes the waterline stripe is tinted getcoat. There was a few spots where I was overzealous with the sander and I can see pieces of fiberglass where I removed the stripe. With the touch method the stripe does feel slightly raised, especially when compared to the gelcoat above the waterline. When I removed a little too much of the gelcoat below the waterline it turned black (now I didn't go crazy, it looks like black orange peel).

I think I am going to tape and paint the stripe first (white) and then re-tape the line and paint the rest of the hull. But before any of that gets done I need to spend a lot of time fairing everything out.

With the sail number. I don't know my EXACT sail number... My hopefully-original O-Day sail doesn't have a number but the sail bag it came with says 2902. My title says I have a 1971, however it might be closer to a 68'. I'm waiting for my DSA members book to arrive so I can try and get an estimate on model year. (Since the hull number plaque is missing off the front flotation tank).

Good luck. I'll be posting more pictures as the hours pass working on her!

Marc

[Wyatt]

Hi Marc:

Yes, I'm about 1/2 mile from the Brass Castle Road intersection with Rt. 57-- Grand Avenue to be exact. So if you are ever in the area and have some time, give me a call at 908-835-8841 and I'll show you my project.

I used a 7-8" electric grinder with 24 and 36 grit pads. The blistering has actually extended into the outer mat layer of the hull itself, so I am going to take that down and reglass using 1 oz. mat. In the flexing and damaged areas, I plan on going over the mat with 10 oz. fabric and another layer of mat. Then refairing. I need to learn how to make a straight and curved fairing board.

Since the boat was upside down, I took the opportunity to build a new centerboard using Dave Misunas's instructions and a NACA 0090 profile. Used a 2x10 from Home Depot and TAP Marine Epoxy. What a difference from the stock clunker!

You may also want to check out the coaming backers and knee braces. Mine were completely shot and I doubt if they ever did much to support the sides of the deck.

If your boat is 2902, then it's 20 away from mine (2922) and probably a 1967. Caribbean blue hull and white topsides.

Regards,

Wyatt

[Geronimo]

Hi guys,

Sorry to jump your thread, but I wanted to mention to you NJ sailors that we have been doing some low-key racing on the Toms River out of Pine Beach Yacht Club. If either of you is interested, please contact me. There are currently 4 DS-1's and 3 DS-2's at PBYC. I posted more info in the Fleet area (I think).

Also, on the "stringers" topic, one our sailors did the stringer replacement using half sections of PVC and it turned out great.

[MarcCram]

Geronimo,
I would be out there in a heartbeat if I didn't have those nasty cracks in my hull. As soon as I take her on a shake down sail and determine everything is good to go we'll take a ride out and plunk her in.

I hope this is by July of this year.

Cheers!

Marc
Cherry Hill, NJ

[calden]

Hey:

I pulled my boat out for first sail of the season, and checked for hull stringers. Just as I thought - I have none. I think I'll do that PVC pipe trick and put some in. I can feel some flex in choppy waters.

Carlos