mast base corrosion advice sought

Discussion in 'Main Morgan 38 Sailboat Forum' started by terry_thatcher, Oct 23, 2019.

  1. terry_thatcher

    terry_thatcher Terence Thatcher

    Jan 19, 2004
    I rarely pull my mast. 20 years ago, I found it was corroded to the aluminum mast step and we ripped the bolts holding down the step out of the lead to pull the mast. I had the aluminum step sand blasted and anodized, hoping to solve the problem. Today, for the first time in 20 years, I wanted to pull the mast and we ran into the same problem. The mast would nor come off the step and this time, the lag bolts were so well embedded into the lead we couldn't pull them out. At one point, with the crane pulling up, the boat started to rise from the water. Yikes. Finally, after applying heat to the mast butt, having the crane apply and upward pull, and rocking the mast back and forth in the partners, the mast broke free from the step. But now I have a lower mast that is corroded and I am concerned about its integrity. Has anyone else dealt with this corrosion issue? Perhaps for lots of money I could have a new extrusion built to sit inside the existing mast or surround it, then rivet them together to add strength at the base. RigRite, which I have always avoided, might have a few feet of a Kenyon spar of the right dimensions, but I need something either bigger or smaller than the current mast dimensions. Or I could cut some of the base off and raise the step, but that might alter the mast dynamics and would surely add to stress at the partners. I might add that there is corrosion where the spartite wrapped around the mast at the partners, but it appears minor. I welcome any suggestions
  2. Travis

    Travis New Member

    Aug 13, 2018
    Home Port:
    Marina Del Rey

    Some photos might help us judge the corrosion issue. It sounds like the mast is in rough shape to say the least, so it is hard to give responsible advice besides “sounds like you may have needed a new mast 20 years ago”, but I would be curious to see what you’re describing. It might provoke a better response from folks on here too...

    I would not rebuild the step if I were you. It solves problems that you don’t have, and doesn’t solve all the ones you do have. It doesn’t solve your corrosion issue at the partners so you would still have this annoying metal work task whether you fuss with the step or not. Not that I wouldn’t be interested to see the precedent set, but I can’t imagine it would be less hassle than to hire a good metalworker to get your mast brought into serviceable shape at the two locations you mentioned. Again it is hard to say without being able to see what you are seeing.

    What I can say is that if I didn’t trust the integrity of a section of my mast, but replacing it wasn’t possible, and I didn’t have the option to replace just the corroded area with new piece of identical cross section, I’d spline the interior by adding lengths of aluminum to the inside surface of the mast in the affected areas. The pieces should be about the same thickness as the parts they are covering. They could probably be riveted in place to keep cost down. If it’s done correctly, you’ll probably get another 20 years out of it. Sure, you gain some weight, but what is an extra 100-200lbs vs 4+ boat bucks spent on replacing the mast...

    All this makes me wonder how your mast is corroding so quickly. It doesn’t seem to be an issue on most Morgans...
    Last edited: Oct 30, 2019
  3. terry_thatcher

    terry_thatcher Terence Thatcher

    Jan 19, 2004
    Part of the corrosion at the base is my fault. Years ago I altered the mast step to make sure water did not collect inside the mast base and the step. My machinist cut weep holes in the step. But over the years, the weep holes got clogged and I forgot to keep cleaning them out. When we pulled the mast, the interior of the step was full of water. Higher up at the partners, I used Spartite. Although it is supposed to adhere very tightly to the mast, mine obviously allowed some water to get between the spartite and the mast, which then caused corrosion. One of our members years ago said the mast is not anodized, which seems a very bad idea, and I don't really know if that is true. After looking closely, none of the corrosion has yet compromised the mast integrity, in my view, but I don't want it to get worse. I can use lots of TefGel on the base--and I might have my machinist strengthen the base with shims. But I also intend to call Spartite and get their thoughts. By the way, I think that a NEW Mast would be more like $15K, if I were lucky.
  4. chawakee

    chawakee Robert McCabe

    Oct 4, 2001
    Hello all,
    I’m of the belief that most of the water found at the base of the mast enters through the sheaves at the masthead.
    I’ve had my mast down and replaced all the sheaves, there’s easy access for wind driven rain to enter the mast at this location. Now I’d like to figure out a way of blocking the water from reaching the mast step, maybe having it drain through a weep hole below the boom, or creating some kind of shroud that would prevent rain water entering the area around the sheaves.
    Thoughts anyone?
    SV Cha-Wa-Kee
    M-382 1979
    Hull # 169
  5. dave_a

    dave_a Dave Ahlers

    Aug 15, 2006
    Bob, I drilled a 3/8" hole at the base and let the water out into the bilge. My boat was a 383.
    Terry, As Travis said pictures would help. I'd print them up too.
    Depending on how into sailboats your yard is, I'd find the local yards with the best sailboat reputations. Take the service manager the pics and get their opinions. They've likely run in to this before. Also ask who the best welder is they use and contact some of the names and ask them what they might do. The mast is a big old tree trunk, not some thin, bendy, fragile tapered racing spar. I'm guessing it can be repaired. Might be ugly but who cares? If you had to, you could lay the mast on the boat and take it to the best yard. But a mobile welder might be the optimum answer.
    BTW, get some anti-seize at the auto parts store and apply to the inside & seat when repaired. Makes it an easier release.

    I used to pull my mast every year. After you do it a few times, it's no big deal. It takes 3 guys plus a crane operator. Maybe a 15-20 minute process. A couple saw horses, bungees and rope to secure the foil & furler drum and the mess of rope & wires. Every couple years for inspection makes sense in a salt environment?
    Good luck and keep us posted!

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