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Is this serious? Crack at base of mast support

Jul 7, 2015
Hunter 33_77-83 Kemah
I have discovered a crack in the fiberglass box in the bilge around the mast support. At the same time I discovered that all 4 bolts to the mast support inside the cabin were 5 to 15 turns from being tightened, probably an oversight when the mast was stepped a year ago when it was delivered to Kemah from Baltimore Maryland. The crack is facing the bow right down the centerline of the mast.
This is puzzling as it looks like the force from the mast support would have to be applied in bending, not compression to cause the crack. I inspected the top of the support beam and found nothing amis except the 4 loose bolts. I inspected the topside and found nothing worrysome. I will try to attach the photos.
Jul 14, 2015
Catalina 30 Stillhouse Hollow Marina
I do not, nor have I ever had a Hunter. But the vintage year you have it is probably just a fiberglass casing around a wooden support. I would reseal with 5200. I am sure Hunter owners will chime in. The rest looks good.
Jul 7, 2015
Hunter 33_77-83 Kemah
Thanks, that is what I was hoping. I know it does not leak, I put papertowels around it for a couple days in port and they stayed dry. Unless someone has another idea 5200 sounds like a winner.
Sep 30, 2013
1988 Catalina 22 central Florida
The first thing that came to my mind was resin of some kind. Epoxy, polyester ... sumthin? Do they make something that penetrates into cracks like that?


Jun 3, 2012
Hunter 33 Steamboat Wharf, Hull, MA
I have a 1980 H33. I had to replace the entire compression post a few years ago. That crack is in a solid fiberglass block that was cast in place when the boat was built. On mine, I had to chisel that out to discover what was inside. If you look at the top of the compression post you will see an aluminum casting that I call a shoe. On the bottom an identical shoe is sitting on the floor of the bilge. The shoe has a socket that the compression post fits into with a slip fit. The fiberglass is cast around and over the shoe completely encasing it. I have no idea what caused the crack. There may be some corrosion on the compression post inside that block. My suggestion would be to chip the block completely out, inspect the compression post base, and to recast the block with epoxy. Also, your mast base plate is different from mine and may be a later owner modification or perhaps it was an available option from the manufacturer.
Jul 7, 2015
Hunter 33_77-83 Kemah
Before sealing it with 5200 looks like the consensus is cut an inspection port and see what is inside. I'll do that and post pictures of what I find. Can I use a cut off whell to make an inspection port? While wearing a dust mask of course.
Jul 7, 2015
Hunter 33_77-83 Kemah
The bilge pump ( brand new attwood 500) failed last weekend and the bilge was completely full of water.
Replaced with automatic Rule but now I know the area under that fiberglass cover has seen water intrusion.
If the inspection port shows the wood to be sound I can put a fan on the area and dry it out. Will the Rot Fix work to prevent rot from developing?
Jul 7, 2015
Hunter 33_77-83 Kemah
On the bilge pump issue ever since the automatic pump failed I have wished I had a backup pump in place.
Not keen on taking up the flooring to run a separate line to a thru hull fitting I have been pondering a way to use a Y valve to have a second pump ready.
Not wanting to use check valves which could get crud in them and then fail, the solution finally dawned on me.
Use 2 PVC ball valves. Leave the ball valve on the primary pump open. If the need arises to activate the secondary pump close the open ball valve and open the secondary one.
Not as elegant as two totally redundant automatic pumps, but the quickest and most reliable way to use what I have on hand to add capability to the bilge pump situation.
MarineDepot.com has barbed Y connectors.
Jul 7, 2015
Hunter 33_77-83 Kemah
Chiseled off the horizontal top layer and the vertical surface adjacent layer.
This revealed a thick fiberglass structure. On the right side of the picture you can see a cut I made with a cut off wheel. The cut is about 3/8" deep and is still cutting into fiberglass.
Chiseled a notch on either side of the crack till there was no more crack.
Looks like there was no way for water to get into this area as the crack has ceased to show signs of propagation at a depth of approximately 1 1/8".
My thoughts at this juncture are to assume nothing got past the fiberglass block and to re glass the box and call it good.
The first photo shows the top surfaces removed from the right side of the crack. The cut pieces are on the left side of the photo.
The second and third pictures are after the crack has been chiseled away.
Last photo is detail of depth of excavation.


Jun 7, 2004
Oday 272LE Ninnescah Yacht Club, Wichita, Ks.
I agree with the above as wood blocking under that fiberglass may be getting wet......Catalina used wood blocking under the
mast in many 30's and when it becomes saturated with water, the entire cabin top will crack above the deck level from starboard to port due to the downward pressure on the mast....can you get visual access to what is below the fiberglass in the
photo? Pat
Jul 7, 2015
Hunter 33_77-83 Kemah
The only way to get visual access is to completely remove all the fiberglass, which appears to be at least 2" thick.
After excavating 1 1/8" deep there is no more crack. Since fiberglass is waterproof I am inclined to believe that everything below the fiberglass is in good condition. Other than a superficial crack in the outer layer of fiberglass the boat has no symptoms of a deeper problem caused by rot.
I pushed as hard as I could in the middle of the mast support in all directions and it does not budge.
With no evidence that there is any damage, and proof that the crack was not breaking through the fiberglass and reaching the wood beneath, I plan to re glass the area and call it a good day.
  • Like
Likes: Rick D
Jul 7, 2015
Hunter 33_77-83 Kemah
Repair work is underway.
I am also repairing the cover for the wiring at the electrical distribution box.
I pulled the cover off to get access to the wiring lugs to add a new hot wire for the new bilge pump.
Have applied 10 layers to the repair of the box in the bilge so far.
Probably about 10 layers left to build back the area chipped out.
The first picture is the repair in process of the area I chiseled out for inspection.
The second picture is the start of the repair to the electrical box.
Jul 7, 2015
Hunter 33_77-83 Kemah
Another 5 layers applied to the divot after work today, still another 15 to 20 to go.
After it is sanded will cover it in 5200 so it will be white and match the rest of the bilge.
Jul 7, 2015
Hunter 33_77-83 Kemah
Through putting on the fiberglass.
Next step is to sand and then cover with 5200 so it blenDs in with the rest of the bilge.
Going out this Friday for a sail in the evening then will anchor off the Kemah boardwalk and have a few sundowner with the crew.