Prindle 16 in a bad state of repair

I just cut up a P-16 starboard hull that was soft and foam filled. What a big mistake P.O. made. When foam expanded (to 5" on hull side) it created a large bulge in hull side. 2 part foam expands a lot--do not use it. Glassing over top will add lotta wt & look terrible. Simply drill many holes in top skin (tape a stop in your 1/8" drill bit) and inject (with plastic syringe) epoxy resin until it comes out adjacent holes (drilled about 2" apart). Fill divits with bondo, sand & paint finish work. Anybody in So. Cal. have a starboard hull? Pete

Thanks for the heads up on what not to do then! Was more thinking of just sanding back the top of both hulls between the spreaders and laying down 2 or 3 layers of mating to give extra strength. What do you think? Rob

Mating absorbs a lot of resin, adds a lot of weight, and doesn't really add much strength to deck. Buy syringes at West Marine or animal supply and try injection method in cool shaded area. Make sure to drill thru only top skin. Pete

I'm new here, but not new to hull repairs, so this is what I would do:

I think you can "mat" it fairly successfully, but use woven cloth, not chopped strand - it's easier to work with and you can make a lighter repair. Sand/grind the top deck down a bit all over the soft area being sure to taper very gradually at the ends. Then you can layer in maybe 2-4 layers of cloth making sure that each layer is longer than the last as they come up the taper. When you lay cloth, the critical step is to use a roller to squeeze out as much resin as you can. Wet and lay down the first layer and roll it, then add another dry layer and roll that into the first. Take your time so the whole second layer gets wetted with resin from the first layer: you almost certainly won't need to add any more. Then do a third dry layer just like that. At this point you may need to slap on a bit more resin with a brush in areas that are running dry. I doubt you'll need though. You could go for a fourth layer if you want.

The key is to be diligent about rolling, making sure the cloth gets wetted through but with no excess. That way you end up with a strong, light repair.

Some supplies:

www.uscomposites.com. Pick a resin: not sure whether you need polyester or epoxy for a Prindle but you have to get the right one or it won't bond. maybe someone else can advise. Pick a slow-cure resin to give plenty of working time.

Here's the kind of matting you need: http://www.uscomposites.com/cloth.html. I would go with the 7.5oz E-glass since it's really easy to work with and wet out. A few laters of that will be plenty strong.

Brushes and rollers: http://www.uscomposites.com/brushes.html or pick them up from your local DIY store.

Tips:

Mix up your resin in a pot then pour it onto a tray - that will slow down cure time and prevent it all going off in the pot (and potentially melting it with heat build up!)

Use a hard, non absorbant roller since you need to squeeze the resin into the cloth.

When brushing on extra resin, be sparing and use the roller to spread it.

Overlap the cloth over the edges of the repair - it's very easy to trim and smooth after it's cured. You may need to finish off the edges cosmetically which will require a layer of resin with a fairing compound to make it sandable. Like this: http://www.uscomposites.com/fillers.html I like the SM fairing compound.

Good luck!

Listen to Pete and search this forum for epoxy injection or deck repair. Very simple to do and will stiffen the decks nicely. Really a very simple process and much cleaner and faster than glassing over the decks.

+1 on Petes comments
The drill and inject method works well and is pretty straightforward and easy
I have used it on a number of projects including foam filled rudders and center boards, all with great success and relative ease
Took a sunfish centerboard from trash to like new a couple of weeks ago and can stand on it to right the boat after the repair. Rock solid
It would be much simpler than layering on mat with epoxy, and you have far less sanding and overall hassle.
One other point if you end up with a mat repair. I use a stainless roller with ridges from west marine that works well to press in the liquid to mat, and you can clean up with ease and reuse it

Agreed on drill and inject - definitely your first approach. I just wanted to point out how to mat without adding a bunch of weight.

http://www.thebeachcats.com/news/400/Soft-Deck-Repair/

http://www.thebeachcats.com/news/87/catamaran-sailboats-delamination-repair-instructions/

Above are links to soft deck repair, please read carefully, it has pics to accompany directions, so easy even a cave man can do it. The core understanding to injection repair is to know the construction of your boat, the above repairs are done on foam core construction, an inner layer of fiberglass on which foam is laid, and then covered by an outer skin of fiberglass, glass/foam/glass sandwich. Delamination occurs when one layer of skin, usually the inner layer, pulls away from the foam. When drilling holes for injection repair, the drill bit must penetrate only the outer skin, use a drill stop, piece of tape wrapped around drill bit to do this. Too often on this repair, do many skip this step and drill bit penetrates both outer and inner layers of glass, letting resin or epoxy mix drip into hull interior.

In one of the above methods, the repairer uses sheet metal screws which penetrate through the outer layer, through the foam core and through the inner layer, when the screw is tightened it pulls the sagging inner skin back up to the foam layer. This method is optional but not necessary, the only pro I see to this method is weight savings, instead of filling the cavity left by the sagging inner skin, the sagging layer is pulled back up and adheres to the foam. The weight saving would be on a very large soft area, the screws would plug holes made through inner skin, but as inner skin is pulled up to foam, much of what was injected would ooze out through the other drill holes. This is where taping off the area being worked on would pay off, when repair is complete, just pull tape off.

Whatever method you choose to use, the key to injection repair, do NOT penetrate inner skin

HTH
R

Thanks for all you help and advise. Will try the drill and inject method in the next couple of days and let you know how it all went. Not many other options living in Uganda! Regards Rob

Niles, let me get this right, you are living/working in Uganda and you came across a Prindle 16 in the middle of Africa, where the Crocs grow up to 20' in length and the Hippos weigh in at almost a ton and you want to get this old cat sailing again?

You have huge brass ones buddy, having grown up in Africa I know 😀

R

Oh to have a lake the size of Lake Victoria in California!haha Seems like there is a lot of great sailing on parts of that lake.

It's not the croc's that you have to worry about, even a slow old cat can beat them. It's the big ,fat hippo's that are the problems. Great lake to sail on though. 74 to 78 degrees water temp all year round. And some great fishing!

dunno which is more amazing, the fact that there is a Prindle 16 in Uganda or the fact that you are prepared to sail Lake Vic, be interesting to see your "righting technique" the first time you flip the Prindle :rofl2:

Been thinking about that myself. My sailing partner has never sailed as well. Might have to have a few dummy runs in the shallows.

I think ANY righting technique may involve walking on water! luckily a Prindle 16 comes up reasonably easy. Hippos kill a LOT of people in Africa every year.

We are pretty lucky where we are, right at the source of the Nile River there is no hippos or crocs but if we sail out a bit.....

nilespecial1 wrote: We are pretty lucky where we are, right at the source of the Nile River there is no hippos or crocs but if we sail out a bit.....

Pretty cool, would like to see some pictures from your sailing launch area. Do you have a sailing club to keep the boat? What other sailboats are with you?

Hi Damon, There is a sailing club in Entebbe but nothing in Jinja where I am based. I have a plot on the water front that I work out of for business. No cat's but there is an old Cornish Shrimper that a mate has. Is there a trick to uploading photo's, cant seem to work it out. Rob

Rob, what news on that soft deck repair?

R

Even if your injection does not fully fix your problem it will improve it a lot and you can still do some surface glass if you think you need it.

I did injection on a Hobie 17 and it did not go well at all but it is still 80 stronger than it was before I started.

OK,
Update on my Prindle. The injection method did not really produce the result that I had hoped for. Some parts are really firm but some are still soft and then when I sat on them it cracked again. Will try a layer of glass mat over the top and see how that goes. Hopefully with both it will hold up.
Cheers Rob