Hole through Luran on Bow: Repair suggestions requested

[CoralRose]

Hello all,

I somehow put a hole in my Luran on 10-24-20 when I was moving my Hunter 23 (1987 model)! I don't even know how it happened. But, I assure you that I was greatly saddened when I saw it while I was putting the her, the Coral Rose, into her winter storage barn. I have never worked with Luran before (I bought this, my first sailboat, in Nov-2018) this. In addition, I have not done any fiberglass repairs.

It appears (you can see the photos for yourself) that a 2.5 inch curved section of the Luran was knocked off and the foam layer is also gone. You can see the fiber reinforced plastic (FRP) evident in the bottom of the hole.

I was thinking that perhaps I could just do a fiberglass repair as described by West System Fiberglass Boat Repair Kit instructions: this is basically fill the space with cut pieces of fiberglass and each layer is then saturated with West 105 Epoxy/406 filler/206 hardener mixture. Build one layer on top of the other until it is slightly taller than the original Luran. Then sand it until it is exactly the same shape and height as the original Luran. This might not give a perfect color match (I do have the whitener that West System sells to go into their 105 Epoxy mixtures and could add whitener until the whiteness of the Luran is matched. There might be a slight difference in color when the fiberglass repair cures but I am prepared to live with slight difference in color).

Can I ask for someone (perhaps Crazy Dave Condon) to suggest a repair that will be strong and waterproof - obviously I don't want water trickling into the Luran/fiberglass joints of the repair if the joints don't seal watertight?

What do you folks recommend?

Thanks,

Mark
Owner of the
Coral Rose
(Isleton, CA, USA)

 

[Hunter216]

As far as I know the Hunter 23 was NOT constructed using Luran but more “normal” FRP - gelcoat materials.

From the user manual

https://sbo.sailboatowners.com/downloads/Hunter_23_24113457.pdf

There is a dark rub mark in the damaged area, did you hit a dock? . I ask because a hard contact might have caused other damage not easily seen.

 

[rgranger]

I agree with @Hunter216

Remove the bulkhead to the anchor locker area and inspect from the inside. If you don't see any cracks there, you can probably just fill in the hole with some filler. To get a smooth finish, mix some thickened epoxy with some small pieces of chopped mat fiberglass, then put it on a piece of velum (like what you used to use in an overhead projector)

Pack the hole and tape the velum over the patch until the resin sets. The velum will hold it in place and give you a nice smooth finish when you remove the velum. Then I would cover the entire mess with some "trim" in the form of a keel guard product like this...

They come in many different colors and it would not even look like a repair job... it would just look like you put on a guard for the next time you kiss the dock.

 

[sandpiper10471]

Looks like fiberglass to me. Due to the shine on the substrate I think it possible the inner layers were not properly bonded to the outer layers. Could have been a Friday/Monday layup? Also, outer layers next to the gelcoat could be vinylester laminate. In any event, polyester repair would be most appropriate.
Please, never use epoxy resin with chopped mat unless the mat is stitched and made specifically for epoxy.

 

[Hunter216]

Please, never use epoxy resin with chopped mat unless the mat is stitched and made specifically for epoxy.

I’ve heard this before but am not sure of the reason. Can you elaborate please?

 

[rgranger]

I’ve heard this before but am not sure of the reason. Can you elaborate please?

I have not heard that one but for repairs I believe epoxy is better than polyester resin. Polyester's main holding power comes from chemical bonding between layer and the mechanical bonding (adhesion) is not as strong as epoxy's. So once polyester is fully cured you need to make repairs using epoxy if you want a strong bond between layers. The down side of epoxy is that it is not UV stable so you need to paint it or cover it somehow. Some nice things about working with epoxy is the low odor and the fact that white vinegar will completely dissolve it while it is still in an uncured state. Even if it is mostly cured... (but not fully) white vinegar will remove epoxy. So clean up of tools etc. is much easier with epoxy. Some people develop severe alergies to epoxy so it is best to keep it off your skin and wear a carbon filter respirator (3M at Lowes). I wear long sleves and a respirator and keep a roll of paper towels and a bottle of white vinegar handy.

 

[Hunter216]

I have not heard that one but for repairs I believe epoxy is better than polyester resin. Polyester's main holding power comes from chemical bonding between layer and the mechanical bonding (adhesion) is not as strong as epoxy's. So once polyester is fully cured you need to make repairs using epoxy if you want a strong bond between layers. The down side of epoxy is that it is not UV stable so you need to paint it or cover it somehow. Some nice things about working with epoxy is the low odor and the fact that white vinegar will completely dissolve it while it is still in an uncured state. Even if it is mostly cured... (but not fully) white vinegar will remove epoxy. So clean up of tools etc. is much easier with epoxy. Some people develop severe alergies to epoxy so it is best to keep it off your skin and wear a carbon filter respirator (3M at Lowes). I wear long sleves and a respirator and keep a roll of paper towels and a bottle of white vinegar handy.

I’ve never worked with polyester, just epoxy - didn’t know the vinegar thing (would any acidic liquid work or maybe this isn’t a PH thing? )

Absolutely agree with the acquired allergy point. A good friend that made a lot of windsurfers developed the problem, changed his lifestyle!

I think the cost of poly is less than epoxy so likely the reason it’s used in volume manufacturing such as boat building.

 

[rgranger]

That is a good question. And I don't actually know the answer so I went looking at the chemical structure a little more. When looking at the structure of epoxy polymers from an Acid/Base perspective, it is not obvious how vingar would attack epoxy... but it would atack the hardener ...which is a tetraamine... typically this...

and each of those nitrogen atoms can accept a proton from an acid at the place where I drew those double dots. And when it does it would become ionic and water soluble. Vinegar is typically 5% acetic acid in water so my best guess as how it works to clean epoxy is the acid protonates the hardener before it has become completely bound up and it gets pulled into the aqueous phase of the vinegar and drags the rest of the epoxy with it as a slurry.

 

[rgranger]

I’ve never worked with polyester, just epoxy - didn’t know the vinegar thing (would any acidic liquid work or maybe this isn’t a PH thing? )

But it does work... it is like cutting grease with gasoline. But once the epoxy has fully set... vinegar wont touch it. So I'm thinking my hardener hypothesis might have some teeth.

 

[isaksp00]

That sure looks like my H23, '91. It is not Luran, and no foam layer. It's just gelcoat on top of the fiberglass. Hard to tell, but it may just be the gelcoat that cracked and the structural glass is not damaged. If so, you would not have any leaks. You could just use, as an example, West systems epoxy to patch it as described above. If you want to try to get it somewhat nice looking you'd probably want to use gelcoat on top, wet sanding it with increasingly finer grades of paper. It'd be hard to exactly match the color though.

 

[Crazy Dave Condon]

Ok, let’s start in layman’s terms. That boat is identified as a Hunter 23 1987 model built out of fiberglass and gel coat. The poster first started saying Luran. Luran is associated with those plastic sailboats first built by JY and then later in Florida by Hunter. When the manufacturers changed formula for the plastic sheets, here comes those damn cracks. Yes you can use fiberglass mat emeresed with Plexsus which is on the backside of the construction foam for strength. I saw the plastic boats being built. I was not a fan of plastic boats.

As for white vinegar it is a good additive for cleaning while apple vinegar is good for adding to Popeye’s spinach as some of us old farts need it to build up them thar muscles. Please no more molecular crap explanation as it goes over my cotton pickin brain. However White lightening is good fur sippin and cleaning. Please no molecular crap on moonshine. So to the point keep it simple and stupid fur all of us cotton Picken brain heads. As for the boat it is the wing keel 23 in this case
First as I enlarged the photos around the edges, it appears maybe a layer or two of fiberglass was damaged. Pleas retake your photos in daylight not at night time for better clarity. Then I can better assist in layman’s terms. However, all the cracked gel coat would have to be removed first with sharp chards sanded smooth. Then I would add fiberglass with either polyester or vinylester resin as you are above the water line. If below the waterline, only vinlyester resin as it is not pourous like polyester resin. Then I would add a two part epoxy which I used Water Tite which was the best when I was a dealer. Sanded smooth with wet and dry sandpaper.
Now for painting. Sure you can apply gel coat but you need a minimum temperature of 64 degrees for drying over 24 hours. You have to make sure the gel coat has a wax like additive in it so the wax will rise to the top to allow the gel coat to dry. If not, the outside will not dry. Some gel costs come now with the additive. Pleas no molecular crap as I got a cotton pickin peabrain. Some gels now come with it while others don’t. In a sense it is like a plastic paint. Here we go again with plastic. Now in reality terms, I would suggest a spray on plastic paint that matches close to the white gel coat by Krylon. Yep another plastic paint but sure dries fast with that fast dry additive in it.
@rgranger. Krylon Paints was started by a mountain boy t gaduating from VMI, not the Citadel who probably sipped some mighty good sippin mountain water called MOONSHINE. The boat is 33 years old, so I would suggest using Krylon but do use a color chart first to see what match’s close. Even if you got the right gel coat color, it would not match but would be noticeable so the suggestion of a fast spray plastic paint.

Now better pictures. Where do you sail

 

[rgranger]

Please no more molecular crap explanation as it goes over my cotton pickin brain. However White lightening is good fur sippin and cleaning. Please no molecular crap on moonshine.

You just beggin' for a lesson... ain't-ja-boy

 

[sandpiper10471]

Re my post of Dec.7: Chopped mat strands are held together with a chemical adhesive. That chemical dissolves in polyester or vinylester but not epoxy. Please don't ask me for the chemistry. Ergo, if laying CSM with epoxy, the resin won't fully saturate or adhere to the strands, thereby not achieving maximum strength. Yes, it can and does work but is not the best use of either product. That is why stitched chopped mat is made for epoxy.