Cracked Radar Arch

S

Sky King

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17791
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98 Regal 292 Commodore with an aluminum radar Arch. I noticed a crack that starts less than an inch from the base on the port side. Starts at the rear and comes around to the inside rear. It's about an two inches long. No sign of impact or damage of any type to the entire arch.

A friend told me that if water had leaked into it and froze during the Winter it could have caused this. Plausible? Any one else experience this?

I can't have it welded as the crack is only about a half-inch from the fiberglass and I really don't want to attempt removing the arch unless I absolutetly have to (well, ok...what I meant to say was didn't want to spend the money to have it removed; got a feeling it won't be inexpensive)!
 
If you are not going to get it fixed make sure that you find the end of the crack and drill a small relief hole in the arch. This will stop the crack from growing. Yes I know it sounds silly but it relieves the stress and has to do with fracture mechanics. As far as water in the arch I am not sure but I will be thinking of this coming up this fall.
 
i dont know about your specific arch, but i can tell you that two of the regals ive had have an alum arch. both had an alum frame and both had a significant amount of faring on them with a paint finish to match the gelcoat. if yours is constructed like mine, and i suspect it is. you will have to remove the arch and grind away the faring before attempting to weld it.

pulling the cables out is not really a big deal. just use a pull string that you leave in place on the way out. there is likely one in the arch from the installation already. its a good opportunity to address any corrosion issues and refinish the arch while its off the boat.
 
Can you tell if the crack goes all the way thru? The arch is painter I believe with gel coat as mine has a few small cracks around some screws because they were not reemed out enough. The arch is just bolted on with I believe 4 bolts on both sides. That is what I remember anyway when I was running my GPS cable thru there. It shouldn't be a real big deal to remove for repairs.
 
Great advice on drilling a relief hole! Had completetly forgotten about that technique. Going to the boat today and I'll get that done ASAP. Patrick, the crack is all the way through, almost like a tear and the upper part of the "tear" looks like it is pushed out about 1/32 of an inch compared to the lower part of the crack. I'm not positive how it's attached but I think through the bottom. I had to remove the inside of a cabinet to gain access to shift cables (replaced last year) and I think I remember seeing nuts below the arch. The port side will be hard to access without removing the wrap-around seat. I'll look into it. Ultimately, I would like to get it repaired. Is the paint a gel coat or an epoxy paint? Thanks for the input from All!
 
gelcoat is not installed over alum. use awlgrip to have it repainted. if you are not experienced in using awlgrip, its best to give it to a paint shop that is. its a great product when used properly and a really big mess if an amature gets into it.

it might be worth the trouble of putting some air pressure into the arch after the repairs are done to be sure there are no other places where water can get in other than your antenna connections.
 
I had the arch removed and a hardtop retrofitted to my 3860 just over a year ago. The port side of the arch had a significant amount of water in it when removed. There was nowhere for water to drain until it reached the level of the speaker. The starboard side had a hole through to the hull for cables to pass and that kept it drained on that side but port side had no holes except for the bolts. Interestingly, the OEM hardtop had what I believe were designed drain holes at the rear of each arch attachment point. It appears to me that Regal learned that the arch was not always waterproof and now provides a way for the water to drain out. You may want to make sure when your arch is re-attached that you have a way for any water that gets in to drain out.
 
PJS, thank you for the insite. I could not understand how, if the water froze, it could crack out the aluminum as any water in there would simply have expanded upwards. I read this to the gentleman that originally suspected ice as the culprit and his response goes hand-in-hand with what you are saying. We normally don't get a "hard freeze" in Charleston, SC but climate change (global warming!) had us absolutely chilled this past winter. With windchills in the -0 range, my friend said more than likely the water froze up high which left no room for expantion when the rest of it froze. Crack! It all falls into place. All this time, I thought I had done a great job of sealing every posible water entry point. Ok, I was wrong and will make sure there is a drain hole once I have it repaired and reseal everything. Again, thanks to everyone that responded! Safe and happy boating.
 
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