Inspection port in mast?

[JeremyFowler]

My Cavalier 39 has a massively strong (IMHO) aluminium mast. What do the knowledgeable ones think of putting a smallish inspection/maintenance port near the base of the mast? It would obviously be circular to shed the stresses a bit, and maybe 2 smaller ones on either side would be better than 1 bigger one? The purpose being mainly for inspection, but also to be able to service electrical connections. The port/s would be closed normally with an aluminium or plastic cap which would be glued closed.
I wonder if fore and aft, or port and starboard would be the least stressed?
Yes? No?
Any knowledgeable advice valued.

[Uncle Bob]

Originally Posted by JeremyFowler

My Cavalier 39 has a massively strong (IMHO) aluminium mast. What do the knowledgeable ones think of putting a smallish inspection/maintenance port near the base of the mast? It would obviously be circular to shed the stresses a bit, and maybe 2 smaller ones on either side would be better than 1 bigger one? The purpose being mainly for inspection, but also to be able to service electrical connections. The port/s would be closed normally with an aluminium or plastic cap which would be glued closed.
I wonder if fore and aft, or port and starboard would be the least stressed?
Yes? No?
Any knowledgeable advice valued.

Mine has a double turning block for two internal halyards, held in with four metal thread screws which allows access to the electrical junction within.

[Manateeman]

Keel or deck step? Do you want to rewire. Where do the wires terminate now.
Ideas from other owners? Photos would help.
Manatee gang

[tkeithlu]

Masts are unusual beams in being stressed in all directions. There is no stress-free area, unlike a usual construction beam. I would be hesitant to add a hole of any useable size without a very careful stress analysis and a good reason for doing it. Is the lack of a port presenting an otherwise unsurmountable problem in your refiting plans?

[s/v Jedi]

Our Forespar masts have inspection openings just above a water separator above deck. You need access to guide wiring through the water separator and also to clean when drain holes plug up.

They have lids with gaskets, fastened with machine screws all around. The openings are oval and small but I can just get my hand in.

[Stewie12]

I too would be dubious about making any holes in mast. Fine if it was designed that way, but otherwise I would leave it alone for reasons given in other answers.

[FabioC]

Before touching any mast, I think it is a very good idea to get approval from the mast manufacturer.
We wanted to add a halyard and needed to add a new exit point. We called Selden and gave them the dimensions and our preferred location of the exit point, and they came back shortly after with their approval and a recommendation on where to put it.
In general, I would agree with the other replies, unless there is a compelling reason, it is probably best to avoid making holes on a mast. Not sure "inspection" is a compelling reason... couldn't you inspect enough using one of the existing openings (perhaps with the aid of a wire camera?)

[Manateeman]

We posted the question of how best to close off a halyard slot of about 3/4 x 2 on the boat design net. We got an avalanche of comments. You name it, they stood firm on the engineering of every idea from don’t do it to how to weld it closed.
Very difficult to get any agreement.
We’ve seen inspection plates so big I can squeeze my hand into them.
We’ve seen holes just large enough for a fiber optic camera.
Again, our question is ...what are you trying to accomplish and why.
Thanks..Mark

[Searles]

The cavalier 39 keel steps mast is a real pole have cut a 50 mills hole in one about 150 mills above heel for wiring access epoxiedcut out piece back in no probs ,big heavy masts access ports within reason not uncommon in this part of the world , would hesitate to do on a thin racing mast and no way in carbon ,.⚓️⛵️��

[JeremyFowler]

Thanks for the input.
To answer the questions: the mast is down atm. The aim is to be able to service plug in connections that don't exist at the moment. At the moment I'd have to thread all the cables through a 20mm flexible conduit and do the terminations inside the cabin. The mast is deck-stepped. I'm guessing it's about 5mm thick aluminium, oval about 210mm by 140mm. Really chunky, and I'd guess that it at least double the needed minimum strength.
Uncle Bob's comment could be the way out. I could enlarge slightly the access for the halyard turning block. That will give reasonable access for a small hand (not mine) and should only marginally increase any stresses.
Thanks! from the ends of the earth...

[Manateeman]

How do the electrical cables exit the mast now? A few photos would help. We take it that you are not replacing the existing mast wires? What’s up top.
There are a lot of waterproof connectors to choose from and the members here have a lot of experience with the good and bad examples.
Photos or a drawing would help.
Mark

[OS2Dude]

How often do you un-step your mast? How difficult is it to thread the wires down the conduit when you do? Most boats I've seen removing the mast either have connections below deck (usually keel stepped boats) as yours seems to, or the crane operator lifts the mast 6 or so inches and the connections made/broken then (Deck stepped). There is always the dubious option of having the wires leave the mast via a grommet and having deck seal connections. (Had this on first boat, leaked and looked bad IMO.)

[MikeHoncho]

mine has a 1 1/2 hole in the side of the mast about 3 inches from the deck stepped base. The hole is obviously not original and was there when I bought the boat. It has made the ability to run the in mast wiring through the deck manageable.