Hunter 170 crack down to keel

[DFD]

2002 Hunter 170. I’m used to repairing cracks on the deck, however, just noticed this winter, a crack, running down the side all the way to the keel.
Will plexus work on the sides and bottom for repairing or is there a better method? Thanks.

 

[Ralph Johnstone]

You definitely have high stresses occurring under the cracks. This will require building up the hull under the cracks with layers of FG to stiffen up the hull and prevent flexing. Without the reinforcement, the cracks will reappear again, and again, and again ................................ You get the picture. Once reinforced, check with Boatworks Today

Boatworks Today | Boating Help For The DIY

Boating Help For The DIY on Boatworks Today…

www.boatworkstoday.com

................. for the best possible way to fill in the surface cracks. Look through Andy's vids for the very best way to do anything and everything with FG.


Check for any reinforcing currently in place. Maybe it's come loose and needs reattaching. Unfortunately, life isn't usually that easy on a sailboat

 

[DFD]

You definitely have high stresses occurring under the cracks. This will require building up the hull under the cracks with layers of FG to stiffen up the hull and prevent flexing. Without the reinforcement, the cracks will reappear again, and again, and again ................................ You get the picture. Once reinforced, check with Boatworks Today

Boatworks Today | Boating Help For The DIY

Boating Help For The DIY on Boatworks Today…

www.boatworkstoday.com

................. for the best possible way to fill in the surface cracks. Look through Andy's vids for the very best way to do anything and everything with FG.


Check for any reinforcing currently in place. Maybe it's come loose and needs reattaching. Unfortunately, life isn't usually that easy on a sailboat

Thanks! Once it warms up I’ll get started.

 

[Ralph Johnstone]

Please keep us informed.

 

[stickinthemud57]

I'm not sure when Hunterstopped using Loran to make their 170 hulls. Dave??

Putting fiberglass over Luran does not work. Ask me how I know.

It looks like Luran to me, but definitely find out what material you are working with. Plexus is very expensive and caustic. Better to use fiberglass, as long as you are not applying it over Luran.

 

[east coaster]

Please advise me on the material called " loran", after a long range navigation system, long gone; or is it "luran"? I have heard of the former but not the latter, thank you.

 

[stickinthemud57]

Luran. Sorry for the confusion. Per ChatGPT:

Luran® is a trade name for a line of styrene-based thermoplastics developed by INEOS Styrolution. It is primarily composed of ASA (Acrylonitrile Styrene Acrylate) or SAN (Styrene Acrylonitrile), offering high UV resistance, impact strength, and weather durability.

Key Variants of Luran®:

1. Luran® S (ASA-based) – Highly resistant to UV radiation and weathering, often used in outdoor applications like automotive parts, marine components, and exterior panels.
2. Luran® (SAN-based) – Offers good chemical resistance and rigidity, commonly found in household appliances, medical devices, and industrial components.

It's possible that the outer layer of the Hunter 170's ACP hull was Luran® S, as it is known for its durability, gloss retention, and UV resistance, making it a good fit for marine applications.

Knowing whether you are dealing with Luran or fiberglass is very important. Fiberglass will not bond to Luran, Plexus will.

EDIT: I believe that Hunter did not switch over to fiberglass on the 170 until 2025, which increases the possibility that your hull's exterior is made from Luran S. A search at this forum for "Luran" will show you pages of posts that deal with the Luran hull issues, ways to repair, etc.