Fixing cracks

[Papafuego]

I’m a first-time Hunter owner dealing with some cracks in a 1998 Hunter 140. I’ve read a lot of helpful threads about fixing cracks with Plexus, after cutting open the cracks to a 45-degree angle. For anyone who’s familiar with the method could you give me a little extra guidance? Specifically:

1. For very thin cracks, how wide/deep should I open up the crack? I’ve used a dremmel on one already and it ended up being a half inch wide and down to the bottom of the ACP. Seemed like that may be too big for such a small crack, but I’m not sure. Does this sound right?

2. For bigger cracks, after opening them up to 45-degrees I’ve read about soaking fiberglass sheets with Plexus and layering them over the crack. What type of fiberglass sheets should I use?

3. There are a concentration of cracks under the mast step, spidering out in different directions. Would I just follow the same steps for repairing each of the cracks individually or should I do something different to strengthen this area, since it’s placed under so much strain from the mast. I’ve attached a photo of the mast step area (mast step is removed).

Thanks in advance!

 

[RitSim]

What was bolted there? I would want to know what caused the cracks before beginning repair. Was this a case of too much force on the top skin and the load not distributed? Is it freeze damage from a wet core? Cosmetically fixing the cracks and ignoring the underlying damage will only fail again.

 

[Papafuego]

What was bolted there? I would want to know what caused the cracks before beginning repair. Was this a case of too much force on the top skin and the load not distributed? Is it freeze damage from a wet core? Cosmetically fixing the cracks and ignoring the underlying damage will only fail again.

Thanks for the response. The metal bracket that holds the mast was bolted there (you can see it at the top of the picture). I assumed it was the weight of the mast that cracked it but I’m not sure how to verify what the cause was. Any thoughts?

 

[RitSim]

I can't tell what I'm looking at. Is this in the cockpit where the lowered mast sits? Is this where to base of the mast sits when the mast is up?

 

[RitSim]

Any way to view the underside of the cracked surface? BTW, I looked up a pic of the boat and see that this is where the mast base sits. I certainly looks like the area was completely overstressed- full wind jibe, or shroud letting go under sail, or just not handling the mast properly- its one big moment arm. I still recommend looking for under-gel coat damage to the structure.

 

[Papafuego]

Any way to view the underside of the cracked surface? BTW, I looked up a pic of the boat and see that this is where the mast base sits. I certainly looks like the area was completely overstressed- full wind jibe, or shroud letting go under sail, or just not handling the mast properly- its one big moment arm. I still recommend looking for under-gel coat damage to the structure.

You’re right about the location - right where the mast base sits. I’ve attached a photo from wider back to show where it is.

Since there was a piece in the center of the crack that was cracked all around, i pried it off pretty easily. The wood underneath doesn’t appear to have any water damage or warping (photo attached). I could pry off another small piece to see if the cracks extend down through the wood? How else could I look for damage to the underlying structure? Thank you very much for your help.

 

[RitSim]

Wow. I'm not familiar with that particular boat design but a few things stand out. 1) Doesn't appear that there is any glass fiber reinforcement in the resin. 2) The resin is not bonded to the wood below. Both of these are different from what I would expect. The resin appears brittle and the resin/deck flexing is resulting in the cracking.

Perhaps someone familiar with this design can chime in as to whether these are normal conditions.

 

[Crusty Ol Salt]

Wow. I'm not familiar with that particular boat design but a few things stand out. 1) Doesn't appear that there is any glass fiber reinforcement in the resin. 2) The resin is not bonded to the wood below. Both of these are different from what I would expect. The resin appears brittle and the resin/deck flexing is resulting in the cracking.

Perhaps someone familiar with this design can chime in as to whether these are normal conditions.

Reminds me of peanut "brittle" and it looks like the mast was repeatedly dropped into place like a hammer forge causing the issue.

 

[Ted]

The cracks you are experiencing are a common problem with many small Hunter boats including the 140. Hunter used ACP construction that combines thermoformed UV protected plastic with fiberglass mat and injected foam to make the hull. It's unfortunate that many people who purchased the boat are stuck with a long term problem. Take a look at this article authored by Marlow-Hunter.

https://www.marlow-hunter.com/wp-content/export/Miscellaneous/ACP%20Repair.pdf

 

[Tater]

The design resulted in an unsinkable lightweight hull. Life is a compromise.

 

[jssailem]

unsinkable lightweight hull

Until the hull begins to crack.
Then would it be sinkable plastic in pieces?

 

[Crazy Dave Condon]

You need to talk with me on the 140 repairs. Former dealer now retired. Send a private message thru this forum to me. I use to advise hunter how to repair these plastic boats. Include phone number and location.
Crazy Dave

 

[Papafuego]

You need to talk with me on the 140 repairs. Former dealer now retired. Send a private message thru this forum to me. I use to advise hunter how to repair these plastic boats. Include phone number and location.
Crazy Dave

Thanks Crazy Dave, I sent you my info in a PM.

 

[Papafuego]

You need to talk with me on the 140 repairs. Former dealer now retired. Send a private message thru this forum to me. I use to advise hunter how to repair these plastic boats. Include phone number and location.
Crazy Dave

Hey Dave - I sent a couple PMs but didn’t hear back from you, so I’m posting here again to get thoughts from anyone who has experience with the Plexus repair method.

I’ve now fixed a few cracks on the boat using the Plexus method and I think it’s gone well, but the biggest repair still remains. There are many cracks under the mast foot, likely caused by impact or weight of the mast over time (see first photo). As I dremmeled out these cracks I noticed that several of the broken pieces were already detaching from the subsurface so I took those loose pieces out (see second picture - looks like a spider). My plan is to use 10oz fiberglass sheets (wet with Plexus) on the bigger area (the center of the spider), and plexus on each of the spider legs. Does this approach sound right?

Thanks all - this forum has been super helpful for newbies like myself.

 

[RitSim]

Nice prep. Is it possible to lower the wood and add some glass/epoxy to the whole area to provide some additional strength?

 

[jssailem]

Never have used the "Plexus Method". So I looked it up. Here is a descriptive manual of the method for anyone interested.

https://www.curbellplastics.com/Research-Solutions/Technical-Resources/Technical-Resources/Plexus-Adhesives-Guide-to-Bonding

 

[Tater]

FWIW, I had a crack on my 170. It ran from the aft end of the port seat then under the non-slip tape on the deck. I read to immediately temp repair any cracks. I stop-drilled the crack at both ends with a 3/8" drill. I filled the holes with "Liquid Nails". The plan was to come back later with Plexus. I may not! The LN adhesive needs touching-up and the crack needs filling. The color match is close enough for me. Time will tell on this but I spilled this stuff on my driveway 10 years ago and it is still there.

 

[Papafuego]

Nice prep. Is it possible to lower the wood and add some glass/epoxy to the whole area to provide some additional strength?

Thanks! I hadn’t thought of that. Is your suggestion to cut down the height of the entire wood block (including the part that’s still underneath the outer layer) and replace that volume with glass/epoxy? Interesting. The wood block is only about an inch wider than the ”hole“ I’ve made in the outer layer, so it wouldn’t take much to do that. Honestly I was surprised to find a wood block there at all, and I’m not sure if it would cause any other problems to remove some of it. Thanks again for the suggestion.