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mast step and support

B

balthazor

John balthazor
I pulled the mast from my 382 this last week. The mast step is
an cast aluminum piece lag screwed to the inside of the boat.
It appears not to have been anodized. It had sat in water so
long (and the drain hole was plugged so there must have been two
inches of water sitting inside the mast itself) that the mast
and the step had corroded together. When we pulled the mast,
the step lifted out with it, tearing out the lag screws.
Several well place blows with a mallet freed it to tumble back
into the bilge. I have cleaned it and will try to get it
anodized--and we will have to redrill the holes for bigger lag
screws.
Apropos of earlier discussions, my mast is stepped right
on top of the keel and the lag bolts appear to be screwed into
the lead itself.

 
Please, what year and hull number is your boat? Did all of the work look original? Or had anyone been in there previously? I'd like to know what to expect when I have this '79 382 opened up.
Lagbolts into lead is ok, but if you're going to re-fit anyway you may want to consider threaded inserts and bolts. (Just a thought.)
 
Terry,
When I had my mast out of the boat a few months ago, I found that the cast-aluminum mast step was fastened down by a couple of ss studs. I removed the nuts at the top of the studs and pulled the step for cleaning, etc. I didn't remove the studs, but now wish I had.
It sounds like yours pulled completely out of the keel. How long are they? Did lead shards pull out, or did you find lead in the threads of the self-tapping portion of the studs? If so, then the stud must tap into the lead ballast and the stud would be a great place to tie in some copper foil for a better SSB ground plane.
 
The ballast in these boats is not in direct contact with the water and therefore will probably not improve the groundplane. Salt water is a great conductor but it must come into direct contact with the metal.
 
Edward: It looked original to me, although I know that the mast has been out of the boat at least once in the 1980s. My hull number is 163. I don't consider this a big problem--corrosion is a fact of life in salt water. I will talk to my yard about inserts and bolts--although, the idea is that this thing never should come out. At a minimum, we will bed it well--it did not have bedding compound under it from what I could tell. I just have to control the corrosion and I hope providing a better drain and anodizing the piece will do that. Plus, now I know what to look out for. I know we all have problems off and on, but when I look at my 382 and compare it to other 20 year old tupperware boats, I think we are doing pretty well overall.
 
Larry, just like running a lot of copper foil below the waterline and inside the boat will provide a good ground and counterpoise at radio frequencies, so will the encapsulated lead keel. The foil and lead both couple capacitively to the ocean. A large underwater metal object, like a lead keel, will make a good RF ground, even if it's insulated. It's surface area that's important for RF, which is why foil is always used in place of wire for RF grounding.

 
Jim, if you have access to any of the NEC based software try modeling this sometime. It's kind of interesting! The wide straps help reduce inductance when connecting to ground through the through hulls but offer very little capacitance to the water. Same for the ballast. The capacitance required to couple to ground at HF is much greater than at VHF. Xc=1/(2Pi*FC) Larry
 
The 50' of copper foil in my boat has a capacitance of about .01 mfd. This is not a huge capacitor, but at 4 MHz the resultant Xc is only about 4 Ohms -- pretty small. When the capacity to ground due to the keel is added in, the Xc should drop to less than one Ohm, which is much better. I submit that lowering Xc can only lead to better SSB radio performance, especially at those diffult low SSB frequencies. If I can get to the lead in my keel, I'll connect it to my foil and let you know how it all works out.
Jim
 
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