Mast Step And Deck Collar

New Mast Step
New Mast Step

So you have taken the mast out to get some work done or you are simply storing the boat for the winter? Well, now is the time to consider the mast step and deck collar. Just like chain plates, mast steps and deck collars often get overlooked.

Keel Stepped Mast
Keel Stepped Mast

If you have recently removed the mast on an older boat; then it may be a good idea to take the extra time to remove, clean-up, inspect and re-seal the mast step, as well as the deck ring.

Stainless Steel Deck Ring
Stainless Steel Deck Ring, Serviced and Resealed

Usually on a modern day keel-stepped boat, the step is mounted to something solid that should not suffer from water damage. However, I may still use a little sealant around those screw holes just to be safe. The mast step needs to be removed once in a while in order to clean up, inspect and ensure it can properly drain.

Isomat Mast Steps
EWWWW! YUCK! Clean that thing up.

Mast steps that sit on the deck or deck rings (keel stepped boats) can often have screws that go into a wooden core. In this case, if you do NOT maintain the sealant regularly you might damage this wooden core. This can lead to major structural problems depending on the boat’s design.

Rusty Deck Ring
Rusty Deck Ring. Adhesives can Cause Stainless to Deteriorate Prematurely.

If any of these steps or collars are painted or anodized aluminum, it is advisable to have them re-painted or re-anodized (read more on ensuring a long lasting finish here). If these parts are made of stainless steel, clean them, inspect the welds and polish them; it will keep it rust free longer. In either case, go ahead an splurge and buy some new marine grade fasteners as well.

Painted Aluminum Deck Collar
Painted Aluminum Deck Collar

I am not saying that servicing the mast step or deck collar needs to happen every 5 years, but consider it if you know it hasn’t been dealt with in 15-20 years or more. Of course, as all things I discuss, these timelines are general and purely dependent on geographical region and use.  As long as you don’t forget these crucial components and pay them some much deserved attention once in a while, you should have no worries.

Thanks for the read and leave us a thought below.


14 thoughts on “Mast Step And Deck Collar

  1. The last picture in your article looks like Spartite in a Selden deck ring. I like spartite but is it really an upgrade when you have to remove selden’s proprietary mast wedge device?- thank you

    1. This is not an upgrade, merely another option to chock a mast. The Selden Chock System, Spartite, Wooden or Plastic wedges…all achieve the same thing.

      Please note: Spartite is not to leak proof the spar, that is what mast boots are for.


  2. I have a 1972 Morgan 35 and had the mast unstepped. Now that it’s out I find the entire bottom plate that attaches to the keel/hull is corroded away. Do you make a suitable replacement?

        1. You should see one below?

          MIKE K
          April 6, 2021 at 13:38Edit
          I have a 1972 Morgan 35 and had the mast unstepped. Now that it’s out I find the entire bottom plate that attaches to the keel/hull is corroded away. Do you make a suitable replacement?

          April 6, 2021 at 13:54Edit
          Hi Mike,

          You’ve come to the right place. Please send us an email to with any pictures or additional info that you may have.

          Thank You


  3. Hello, I have an unfinished Lyle Hess Falmouth Cutter 26 with an aluminum mast, step, and collar. My boat has never had the step and collar installed (deck isn’t even cut open) and I’m having trouble finding resources on how to properly install the collar and step. Does my aluminum collar need a backing plate? Is there anything that goes between the lead keel and the mast step? I appreciate any help that you can provide me.

  4. I have been unable to find a replacement deck collar for my 1995 Hunter 29.5. The spar is “Isomat”, but any other numbers are faded.

    1. Hi Terry,

      Thanks for contacting us. If you haven’t done so already, check out RigRite. They can be a bit prickly to the touch, but try this link….,%20Mast%20Boots%20and%20Hardware

      Then scroll down and click on “Deck Collars, Mast Boots & Hardware”

      If one of those seems to be a fit based on the description, make sure you note the part number and then give them a call. Prepare yourself no a frills level of customer service, but they are good people. Incidentally they are the only people that still have these as Isomat ceased production many many moons ago.

      If you don’t have any luck, get back to us and we can work out a solution surely. You can also purchase this item through us if you prefer. Just Contact Us and we’d be glad to help!

      Good Luck :-0)


    2. Can you give me dimensions of the spar? The 28.5 ( had an Isomat NG-31. 6.28″ x 4.10″ with integral spinnaker tracks. It was replaced with a similar section sans tracks (IM-180). I’ll bet yours is close to that size. Some of those old castings are hard to find, but if you give me the dimensions, we’ll get on it. -BC

  5. Looking to get a price estimated delivery wait for a stainless mast collar that is similar to that on the Morris Leadership 44 that the Coastguard has in their fleet of 7.

    1. Hi Linda. Thanks for taking the time. Sorry for the late reply the Holiday has thrown us off a bit, plus we just moved into a new facility. Yes, we can make the deck collar that you requested. Do you have a picture of the collar needed. We were part of the Navy Offshore 44 builds and the collars are likely similar, but I am not sure. I imagine pricing to be around $1200-$1800 (excluding shipping) to fabricate a new one from 316 grade stainless steel. We could turn this item around in roughly 4 weeks, so February.
      I hope that this information is helpful to your question. Please let us know if we can help you further.

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