Leaking Mastbase on 83 Oday 28 - Advice requested

May 24, 2011
139
Oday 28 Windmill Harbor Hilton Head, SC
Hello, My mastbase on my 83 Oday 28 has had a leak since I have had the boat (5 years) and its getting a little worse, hasn't been a bad leak but in an attempt to fix this issue I installed a new Mast boot last year and ever so carefully installed it so that there was no possible way for water to enter from this area. Well there is still a leak and I now think it is seeping in from around the mast base itself. I applied a bead of sealant around the edges of the collar (as seen in pics) but still no help. I was considering taping off the area very neatly and spraying some coats of that black rubber spray around the area to see if that helps, any suggestions would be appreciated..

Here is what I believe I hav-

Isomat NG-31 Mast
Isomat NG-31 White Mast Boot (old and was replaced)
Isomat NG28-10: Deck Collar – 5 Bail Type
 

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May 17, 2004
5,071
Beneteau Oceanis 37 Havre de Grace
Can you tell whether the water is definitely leaking at the collar? Keep in mind that a certain amount of water will enter at the mast head and could appear at the base in the bilge that way.
 
May 24, 2011
139
Oday 28 Windmill Harbor Hilton Head, SC
Yes sir, it actually drips from around the hole where the mast exits,
 
Aug 3, 2012
2,542
Performance Cruising Telstar 28 302 Watkins Glen
Is it possible water could be getting into the deck plate? It looks like there may be some deck compression. If water is seeping in around the mast as it passes through the deck, you probably have some water soaking the core in the deck under the mast.
You might use a moisture meter or rubber mallet to check for core integrity. If you cannot tell, you may need to drill some small holes and check the saw dust that comes out.
 

Myauss

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Oct 9, 2016
6
o'day 30 Georgetown
I have a 1983 O'day 30 and I think I have the same issue. What area are you in? Would you care to compare notes?
 
Aug 3, 2012
2,542
Performance Cruising Telstar 28 302 Watkins Glen
I am afraid to look, I taped it all off and bought some of that rubber seal spray, applied 2 coats.
I think by the appearance of those ripples in the deck near the mast, you have some delamination.
 
May 24, 2011
139
Oday 28 Windmill Harbor Hilton Head, SC
Well I did something similar, I bought a can of that weather seal spray stuff you see on TV where the guy sprays a screen door and uses it as a boat? Yeah, well it still leaks so I am not sure what to do now, I am just glad I made it through this hurricane. Other local marinas didnt do so well,,,,
 

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Myauss

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Oct 9, 2016
6
o'day 30 Georgetown
I'm glad you made it through the storm. I'll try this stuff and report back
 

Apex

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Jun 19, 2013
1,197
C&C 30 Elk Rapids
it would look to me, like the potential leak is the groove on the mast. That is a tough area to seal, and water is funneling in there from all 40ft, a lot of water.
 
May 24, 2011
139
Oday 28 Windmill Harbor Hilton Head, SC
Well this is a long story but here goes...while trying to solve the leak problem, another bigger issue was found. The short answer is yes this Spartite is good stuff and looks to have stopped the leak. The bigger issue was that for whatever reason Oday mounted the mast base support plate on a "cross shelf" over the bilge rather than directly on the bilge floor. My only guess is that this was done this way to provide for the shower water to drain into the bilge area?...

A local marine mechanic took one look at my boat and said, "your mast is sinking". So we looked closer and saw that the forward part of the support shelf was sinking/sagging (as shown in the pic). This explained why there was more than a normal amount of pressure on the pin in the mast (which I simply wanted to remove to rebed the deck plate).

So what I decided to do to stop this potential catastrophic failure, was to build a support bracket with 1/4 inch aluminum, 1/2 inch starboard, 316 SS 5/8 threaded rod, 5/16 fiber nuts and SS fender washers and anti-corrosion paint (this is what is shown in the picture), and place it under the sagging shelf then jack/screw the forward/sagging section of the shelf up somewhere to where it should be. Well this of course, required that I loosen all the rigging to allow the mast to be lifted about 1/4 inch.

Well it all seemed to work ok, there where a few snaps and pops as we slowly lifted the shelf but we only went up by a 1/4 inch. I am now n the process of re-tuning all the rigging using one of those Harken RigTune Pro digital rig tension meters, We set the mast rake, centered the mast athwart ship and hand tightend the turn buckles, Next step according to Seldens tuning guide is for a lightr sail to further adjust the rigging....more to come but I thought I would share this adventure.
 

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