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Pearson 365 Main Mast Step

Started by Sandy, December 05, 2017, 11:32:29 AM

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Like every other Pearson 365, the mainmast on my ketch has corroded enough to warrant cutting the end off the mast and replacing the step. I used a piece of stiff paper to mark the end of the mast for cutting, because if you wrap the mast with the paper and align the ends, you will get a good mark for a square cut all the way around.

The new step was fabricated out of 316 stainless by an odd job contractor. He got confused about what I was asking of him and forgot to add enough base to replace the height that the mast had lost, but it wasnt a problem to correct that later.

Unfortunately I had to cut away the studs holding the original mast step to the inside of the hull, for awhile I thought that using stainless which is twice as strong as the mild steel it replaced would allow us to get by, with the intention of using what was left of the existing studs furnished with new nuts and washers. But in cutting threads onto the studs one of the studs began to twist out of the hull.

Now that the complete stud fixing could be seen I decided to replace all four with 316 SS coach bolts and omit the studs altogether. The new bolts are larger at 10mm diameter, and run a little deeper at 65mm. I had to drill out pilot holes for these and found that the aft pair drill through the fiberglass and straight into the lead ballast of the keel. The forward stbd hole went into solid fiberglass, but the port side seemed like a void. Ive put some hempels epoxy into the hole to try to give the threads of the bolt something to bite into.

Pictured below,
1/ Zaya looking somewhat forlorn up on hard standing with a myriad of repairs awaiting
2/ The new 316 SS step in situ within the bilge
3/ the stud that attached the old step now out of the hull, with a button die tool still grasping its end

Rudderly Confused

I did mine a bit different.  The new metal step replicated the old, and the amount removed from the base of the mast (about 1 1/2") was made up for with a slab of G10, slightly larger than the base of the mast step, of that same 1 1/2" thickness. I drilled and tapped the G10 for 5/8" studs, screwed the studs into the G10, and epoxied the G10 into position in the bilge. I then set the step on top of the G10, added stainless fender washers and nuts, and tightened it all down.  The nuts can be loosened to adjust the position of the step on the G10 to align the base of the mast as needed.  I also drilled weep holes in the step, and routed drainage grooves into the G10 so that any water getting into the mast will drain out the bottom.  The step and base of the mast are kept above the little bit of water that always seem to collect in that area before draining aft.  Overall mast height stayed the same, and all the stays fit as before.


I am a new owner of a P365 ketch and will be doing this job myself.  The mast has not been unstepped by the PO in 19 years, so I am not exactly sure what I will find when I have it pulled.  I expect that actually pulling the stick might be problematic because parts may have fused, or things might just crumble away.  The boat is a 4-5 hour drive from my house, so I will not be able to check it out for another couple of weeks.

Zulu40, I'm curious why you went with a stainless steel step instead of an aluminum one.  I would think that SS will cause additional corrosion issues on the base of the mast.  Rig-rite sells a custom aluminum mast step (anybody know how much) which is semi-designed for this replacement (they mention the 365 in the write up).

Rudderly, I like the idea of using G 10 under the step to raise it up.  I had thought that I would use wood (a friend suggested I fabricate a new step from wood, but I don't think so), but G 10 is stronger and rot resistant.  I have used G 10 when I replaced the sea cocks in my P30, and it is a great material, if a little pricey.



Made my step on a band saw out of three pieces of phenolic. (glass resin and cotton cloth) Will not rot, corrode or absorb water. I did use SS concrete anchors from McMaster Carr to bolt the pieces together.

Here's how I put it in without having to step the mast. Standard practice in shipyards I'm told.


Rudderly Confused

My mast had been un-stepped for about 3 years when I bought the boat, so that part of the job had been done for me.  It was just a matter of removing the old step, measuring and trimming the mast base, matching the G10 thickness accordingly, and proceeding from there.  I've also used G10 for seacock backing, but as you said, it is a bit pricey.  I've also made my own fiberglass sheets for backing plates with polyester resin and layers 1708 glass.  As Pete said, phenolic will also work well, is cheaper than G10, and less labor involved than making fiberglass sheets.  I try to avoid wood as much as possible, for fear of rot.



I would love to see a better picture of your fabricated phenolic step.  You can't really see much in the link you provided.  Did you build it so it fits a plug up inside the mast rather than uses "wings" on the exterior of the mast (like others I have seen)? 

I don't know where you are that they want to charge $3k to unstep the mast.  In RI, I have the mast on my P30 unstepped every year for about $180.  However, I liked your solution for listing the mast.

I did contact Rig-Rite and got a quote.  They said their aluminum step is $589, which is more reasonable than I expected.  I'm tempted to just buy the one from them because I expect that it will be more robust than one made from a composite material (like G10 or phenolic sheets), though I may be wrong, especially given that I need to step/unstep the masts every year to truck it home.



In any galvanic cell there is an anode(aluminum mast), a cathode(steel mast step, or even just another piece of aluminum that has slightly differing alloys) and an electrolyte (salt water).  Remove any one of those and there can be no corrosion.  Pete's mast step is the ultimate warfare as there is no cathode AND it lifts the step out of the water. (no electrolyte)  There is an awesome drawing with dimensions on another thread here somewhere.

That said, we repaired ours in Panama.  No supplies available to make Pete's step.  LOL, it was totally third world and you'd be lucky to find cotter pins that didn't corrode to dust almost instantly.  There was a banana shipping dock next to us.  So what we did was take a scrap of 3/4 marine plywood, make 3 pieces the size of the step and epoxy (thickened)  them into place,  then glassed over it with some bi axial glass and epoxy I had on board.  Cleaned up the old steel step in a sand blaster and coated it in epoxy paint.  Cut 2 1/4 off the mast and stepped it.  Covered the whole area in LPS3 corrosion preventive.  Total cost about $60 USD  Doing so we removed the electrolyte, so corrosion not very possible.  I'm absotively positive it will last another 30 years.

THAT said, the original Pearson design (flawed as hell) lasted from 1977 to 2015 on our boat, so any thing you do should last as well if not better.   The most important thing is to get it out of the water that is inherent to the 365 in that area. is our cruising blog.


After a number of years of service here is my phenolic mast step. No worse for wear save some dirt and cat hair.


  Non-metallic step is a good solution.


Thanks.  That's a much clearer, closer picture than the one in the other thread.  It's much easier to see how you did it.  I like the idea, and I'll look into it.



Mechanical drawings by Dale and myself (identical designs that we came up with independently) can be downloaded from this site.


I am finally getting to this project (the boat is finally in my yard after a long wait).  Can you offer any details about 3 things:

1.  How is the tension rod attached?  It looks like you embedded a bolt in the block (maybe countersinking it upside down in one layer) and then attached the rod to the bolt with a barrel nut.  Is that right?

2.  From the mechanical drawing that I found, it looks like you just bolted the retaining wings (for lack of a better term) to the block with carriage bolts, and then used longer carriage bolts through the block to hold it down.

3.  Did you ever consider making the through holes into slots to give you some adjustability?


kevin barber

Hey guys,

My time has finally come to replace the mast step.  Where on the site are the drawings to have one fabricated?  I don't see them in the documents section.


Kevin Barber
S/V Pan dragon
1982 Pearson 367 Cutter
Hull 41


  Take the old one to a good machine shop.  They can duplicate it.



Here you go...

I uploaded these pictures that I had downloaded a while ago, before Photobucket blurred the linked images.

Note that Dale's step has holes (fore and aft) to accommodate a through bolt to prevent mast (or mast stub if dismasted) from jumping the step.