Reinforced fiberglass for bottom job?

Hello all -

I remember reading somewhere (maybe on this forum) that someone had used fiberglass with a reinforcing strip in it - I think it was a blue or red strip. I'm going to do a bottom job on the 18 - there's fibers showing through and we have to drag it over a low concrete embankment to get in and out of the water. the hulls have a lot of dings in them already from the previous owner so I plan to disassemble and sand/paint the whole (hull ) thing over the winter. The reinforced fiberglass sounded like the thing to use for the very bottom of the hull - I plan to put a thing strip then overlay with a wider strip. Does anyone remember the name or have a pointer? Thanks - Mike

There are different types of fiberglass mat/cloth, and different materials altogether, but I haven't heard of reinforcing fiberglass. To be honest, the fiberglass alone is plenty strong enough for what it needs to do. Reinforced fiberglass also wouldn't likely hold up against abrasion any better than fiberglass alone. If you really want to protect the bottom of your hull, you're better off buying cat trax.

Also, in order to make a proper repair, you'd want to use both chopped strand mat (CSM) and fiberglass cloth/weave, alternating layers, always starting and finishing with CSM - that's how a typical fiberglass hull is built, the reason being that the CSM acts as a "filler" between layers of cloth, but the cloth adds most longitudinal strength. You also would want to alternate directions with the cloth so the strands don't all line up in exactly the same direction. Also, the polyester resin shrinks as it cures (and ages), meaning that over time, you'll start to see the pattern of the fiberglass cloth through the gelcoat if it's not covered with CSM. However, seeing as your hull probably only needs a thin amount of fiberglass replaced (if any), that would be largely impractical. Most sailors just put a thin strip of tape (or two) in the areas that it's needed, sand it smooth/to shape and then cover it with gelcoat.

Before you go to the trouble of getting fiberglass & polyester resin, cut out the template for the bottom of your hull (use either wood or cardboard) and check it. If you need more fiberglass, there will be a visible flat spot, with a noticeable gap between the template and the bottom of the hull. If you don't have a gap, or only have a gap of 1/16 of an inch or less, skip the fiberglass. Just sand the bottoms with some ~120 grit sand paper to give them a profile, clean them off with acetone and apply gelcoat.

Template: http://static.hobiecat.com/digital_asse ... mplate.jpg

(Also note - if the hulls are very faded and chalky, try buying a low speed buffer and some 3M marine rubbing compound and buffing them back into shape at ~1500-2500 rpm. You can make the hulls look as good as new, no paint required! And it'll give you better results. Paint will chip and peel, and the only solution is to paint it again. Gelcoat only needs to be buffed or waxed to restore the color and the luster!)

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Mike

'79 H18 standard 'Rocketman II' sail #14921 RIP
'78 H18 (unnamed) sail #14921
'08 H16 sail #114312
'97 H21SC sail #238

sounds medieval!

My suggestions would be to find a way to get over the wall without the gelcoat touching the concrete? Can you cover the concrete with wood for this transit? I use PVC 2" pipe to slide my boat over gravel beaches.

In regards to laying fiberglass reinforcement. How much fiberglass has been worn off or is it just gelcoat that worn away?

Can you post pictures?

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Corkguy H18, Tiger, Wildcat

Oh, something else I was going to suggest - get cat trax. If you're launching on a concrete or gravel beach, either Cat Trax or a trailer are definitely the preferred way to go! Especially after you put all that work into restoring your bottoms!

Thanks Sabre and Corkguy!

The boat is down at the reservoir so I'll get pictures next trip down there (hopefully next week). When I bought the boat I could see grey fibers/matrix on the bottom of the hulls so I'm assuming that there needs to be some fiberglass replacement. The rest of the boat has some chips/dents/etc that need to be repaired. None of them seem to be visible on the inside (looks like it was t-boned at one point as there's a big sticker on the side but the interior looks solid). I was planning on taking it apart this winter and sanding/repairing any small stuff and laying a couple of strips on the very bottom (probably 3 now based on your email). I *might* try spray gelcoat but my autobody friends recommend finding a shop to shoot it.

We use PVC pipe to move the boats around on the flat. The ramp is about 20' long and probably at a 30 degree angle. We're in the process of anchoring 2x4's spaced about 2' apart on the ramp to slide the boats on. I've tried the PVC pipes on the ramp and the angle makes it a bit problematic as it's a heavy boat to muscle up the ramp and the pipes make it roll back in between shoves. One of the guys has put carpet down in front of his boat but it introduces quite a bit of friction.

Just because there's glass exposed doesn't mean you need new glass. If it's been mostly beached on sand, it could just be that the gel coat has worn off (the sand forms to the hull, so it doesn't really wear flat so much as U shaped). The question is how far off is it from original? I thought I needed glass too; I had glass exposed at about 3" wide at it's widest point and ~12' long. However, after I compared it to the template, I realized that if I put new glass on I'd probably be sanding 90% of it back off again! Ended up just applying gel coat with a foam roller. Spraying it on will result in a more even coating and will greatly reduce the required amount of sanding, but I figured rolling is easier and less expensive.

Good point. I'll build the template and check when I drag the boat back to the ranch in a month or so. Would definitely be nice just to sand/polish and the paint. Given the abuse that poor boat has to endure, paying to spray on gel coat might be overkill and rolling might be good enough. How did it turn out for you?

Thanks for all the info... the lake levels are getting low so the boat will be coming home soon.

Regarding small dings, etc on the rest of the hulls, do I need to get filler/bondo for those, then foam roller the gel coat on top or is the gel coat viscous enough to just fill those if not too deep?

Small dings in the gel coat only aren't really worth "repairing," imo... they're cosmetic only, and they're a lot of unnecessary work. If they're not too deep, they can be "sanded out." If they're a bit deeper, you'll have to dig at them with a flat head screwdriver or knife to open them up a little bit, then rough it up with some sandpaper and fill them in with gelcoat. You can buy a gelcoat paste kit for minor dings. be sure to leave it "mounded over" a bit - it shrinks as it cures. Then you'll have to sand it flat, sand up to ~1,500 - 2,000 grit (in increments of 200-300 grit at a time and buff the hull back to a shine with a rubbing compound and a polishing compound and a variable speed buffer at 1,500-2,500 rpm.

Dings, dents or chips that go through the gelcoat are considerably more work. You need to sand down the area through the gel coat to expose the fiberglass underneath. Once the fiberglass is exposed, you need to assess the damage. If the glass is chipped/scraped/punctured or splintered, it is damaged and needs to be removed. Damaged fiberglass always appears white and opaque, whereas otherwise the fiberglass will appear darker/somewhat translucent. You need to sand down until all of the damaged fiberglass is gone, then build it back up, sand it smooth and then cover the repair with gel coat. It's terribly involved if you're just dealing with minor scrapes. Also note that a scrape or gouge that only appears to be in the gelcoat may actually be hiding damaged fiberglass underneath, especially if there was a pretty good impact that caused it or if the gelcoat in that area is cracking away from the gouge.

Note that this is the proper way to repair hull damage - it's what the professionals do, and what a really dedicated boat owner will do. Plenty of people take shortcuts here, the question is what you're trying to accomplish. If you just use a filler/bondo/epoxy/marine tex, as many people do, that will work for a "quick and dirty" solution, but it's not a proper repair, and doesn't add back any strength - it just covers up the damage. A proper repair then becomes more work, as you will first need to remove the material from your original "repair" in order to fix it properly.

If you've got an actual puncture through the outer layer of fiberglass, or some moderately significant localized damage, I'd say it ought to be properly repaired. Otherwise, I'd just leave it.

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Mike

'79 H18 standard 'Rocketman II' sail #14921 RIP
'78 H18 (unnamed) sail #14921
'08 H16 sail #114312
'97 H21SC sail #238

Ouch! Well, looks like I'll now get some practice on a deep hole from this weekend. We were coming into dock and got gusted into a rock and the right hull hit hard. At least it's the end of the season I suppose.

It sounds like what I need to do is to remove anything that's splintered and sand it smooth. From other posts it sounds like West Systems Epoxy is the way to go. It also sounded like I should cut up some fiberglass tape and mix in the fibers to the epoxy for strength? I'm guessing that when I clean it out and sand I'll find that it's all the way through to some degree (see pictures below plus the infamous concrete bank). I'm not sure how I'd be able to get inside the hull all the way up front to put backing material - any suggestions? Thanks - Mike

https://catamaranfr2015.shutterfly.com/pictures/10
https://catamaranfr2015.shutterfly.com/pictures/11
https://catamaranfr2015.shutterfly.com/pictures/15

Nooooooooooo! The boat is made from Polyester Resin. Fix with Polyester Resin. No need for West Systems Epoxy Resin, as guys like me, grind out all the mess after you put it in there. If you want to do it right, sand back the Gel coat around the damage and use 3 layers of glass (lots of posts how to do this), fair it out, and re-gelcoat. WITH POLYESTER



Wow, Really? It's only September. I've sailed with duct tape covering an area bigger than that. Besides, you could make that water tight in an hour......

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H18 '85
H18 '89 "Knotty Passion"
H20 '96 "20/20 Vision"
Fleet 259 Central Coast California

Agreed ... only the end of the season because I'm not risking going out in low lake levels again! If I can get it repaired in time I plan on taking it up to Cascade Locks in the Columbia Gorge (with a wetsuit of course).

So the dent/hole is right on the front of the bow. Sounds like I need to sand it all back then rebuild laying three layers of glass running north/south on the front hull lip (small -> wider -> widest)? do I fill the hole with anything before putting the first layer down? I'll start digging through the forums for those posts - at first glance I didn't see anything on repairing the front nose of the hull but I'm sure I'm not the first person to do this...

Ah - ok, found a post from @srm regarding filler material - any recommendations on what to use for the foam core replacement? I'm hoping there's enough of the backing material left so I can use that - I'm still searching for the This Old Hobie - Blind Hole Repair article...

Recommend you review this thread. Two repairs very similar to your damage. I agree that you should use polyester resin for this repair, especially if you ever plan to gelcoat. Also note that there is no foam core in the very tip of the bow - it is solid laminate.

viewtopic.php?f=13&t=33302&p=131704&hilit=Bow#p131704

sm

Ohhh yeaaaaaaaaaa. Gorgeeeeeeeeeee (Last years H18 NACs Cascade Locks)

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H18 '85
H18 '89 "Knotty Passion"
H20 '96 "20/20 Vision"
Fleet 259 Central Coast California

haha - yes - that's what I look like when I'm out there (the boat in the foreground!). I started out my transition to catamarans a few years ago by renting Hobie Waves in Hood River... that was an experience...especially the time we got pinned up against the bridge support after capsizing!

Have you seen the video of the guy wakeboarding behind an H18? ...around the same time as the NACs I believe.