When is mast step concerning?

[Thomas1985]

I have been noticing the deck around my deck step mast seems depressed, but sheds water in rain etc. The deck does not feel spongy around the mast base. No cracks in deck around the step.

I check the post and it seems solid where I can inspect. The stays all have decent adjustment left (unsure how old they are).

Is it normal for there to be some settling of the deck step? At what point is it concerning?

I would assume it settles some as wood shrinks over years? Also I would assume the deck core could compress from all the loads?

What should a person watch for in regards to deck step issues?

[SailingHarmonie]

No matter how old wood gets it does not shrink in LENGTH. Unless it is rotting, your post is the same length today as when it was cut.

There should be no core between the mast and the load bearing members in the hull. That would be a gross error by the builder.

To me, ANY settling of the mast step is an issue that needs very close inspection to find the reason. There is a reason. It is not a normal part of aging of a boat. Once you find what is moving, you can then monitor it and see if it continues to change.

[S/V Illusion]

Originally Posted by Thomas1985

Is it normal for there to be some settling of the deck step?

No, absolutely not!

At what point is it concerning?

?

Immediately!

Find out why and fix whatever the cause(s) are. And if the step or post are wood, it shouldn’t be a a long investigation.

[Thomas1985]

I don’t see any signs of settling other than it seems like the deck step is a low point on the cabin top. Like the deck starts sloping in to the mast from a foot or so away.

But… I watched and water drains off the port and starboard sides. It does not puddle at the mast base.

Is that just how the cabin top is shaped? I might just be paranoid…

The part I feel would be rot prone is where the compression post goes through the sole into the bilge to the base on the keel. It looks to have been wrapped in fiberglass that’s now cracked open.

[psk125]

The base of the compression post is the first place to look to see if it has done any settling. From your description it looks like a previous owner tried to fix it and his or her "fix" has failed and needs you to open it up and see what's going on down there. Shims might be all that's needed to get the post back in the right position, or you may need to replace a rotted section of the post or the entire area under it may need rebuilding. If water is still not pooling on the cabin top it does not sound like it's gone too far yet.

[Thomas1985]

Ya it looks honestly like someone half ass wrapped it in one layer of glass mat.

Should I glass it back or just leave it bare?

[GordMay]

Originally Posted by SailingHarmonie

No matter how old wood gets it does not shrink in LENGTH. Unless it is rotting, your post is the same length today as when it was cut...

Different species of wood shrink different volumetric percentages, in the tangential [width] & radial [thickness] directions, vs the longitudinal [length] direction, as it goes from the green to the oven dry condition.

Wood shrinks and swells the greatest amount in the tangential direction [±3 - 12%], and about half as much in the radial direction [±2 - 8%], with only about 0.1% to 0.2% in the longitudinal [length] direction [± 72 thousandths of an inch, in a 6 Ft length].
Because of its small magnitude, shrinkage in the longitudinal [length] direction is usually ignored, in most design problems.

As a log, or board, dries, it shrinks more in circumference, than the corresponding shrinkage in diameter will allow.
It is this difference, between shrinking in the radial and tangential directions, that causes splits to develop, in the ends of logs & boards.

Plywood, with the grain direction of each ply oriented perpendicular to the adjacent ply, greatly benefits from the low longitudinal shrinkage of wood
As a result, the rates of dimensional shrinkage, for the width and length, of a plywood panel, are typically less than 1%, [though changes in thickness still remain about the same as solid wood].

[GordMay]

Originally Posted by Thomas1985

I don’t see any signs of settling other than it seems like the deck step is a low point on the cabin top. Like the deck starts sloping in to the mast from a foot or so away.

But… I watched and water drains off the port and starboard sides. It does not puddle at the mast base.

Is that just how the cabin top is shaped? I might just be paranoid…
.

I’m surprised, that a ‘true’ depression doesn’t collect water.
Could the apparent depression be illusionary?
Does a straight edge, in any plane, reveal a concavity?

[Thomas1985]

I agree it’s craziest looking thing I ever saw!

I’ll take a 4’ level to boat next time as a straight edge. I was completely convinced water would puddle. I totally expected a 1’ diameter 1/2” deep puddle to form.

So, I grabbed a glass full of water to conform my fears…

Poured it at the front of the mast bast and it ran around the mast then shed off both port and starboard side. The water also drained at the same location bow to stern on both sides.

This left me scratching my head thinking “well maybe that’s how it’s supposed to be”?

[Searles]

Never ever use ply wood even so call ed marine ply in a mast step or mast base,solid only in the mast heel or deck head ,this is a verry important area in any sailing vsl,if in dought check and check again ,a good surveyor is your best friend ,⛵️⚓️

[Thomas1985]

My boat is generally built like a brick shithouse so I don’t doubt Downeast built it right.

I’ve never seen the deck core in that location. That was just a thought I had when I began worrying there was a depression.

Once I remove the glass slathered over the compression post in the bilge should I reglass if it looks good/ after remediation?

[thinwater]

My boat had sort of a flat spot under the mast because although the deck was crowned, they put a ~ 18" square flat pre-laminated carbon fiber plate under the base of the mast.

[Searles]

I wonder wot the glass slathered over the mast heel or mast step is hiding ,the may hide the answer ,get the muck out and have a verry good look with a good light and mirror,happy hunting.⛵️⚓️

[PippaB]

I have worked on/repaired two boats with settling compression posts/deck steps. In both cases the top and bottom were on wood, and the post was a pipe/tube with no end caps. As a result the pipe’s bearing surface was just the wall thickness of the pipe. Over time this compressed the wood, on both ends, to the point that there was a depression on deck and a “plug” of wood inside the post at both ends.

For repair, we slacked the rig, lifted the deck and mast with a jack, made some epoxy repairs to the wood, slid some metal plates under both ends of the posts to provide a more solid seat, lowered the mast, retuned the rig.

[Thomas1985]

I guess my next step is remove the glass and check that post out.

Mine is definitely wood post sitting on some sort of fiberglass base in the bilge.

I’m not really sure how to get a good look at the top where the post meets the cabin ceiling… that may require some interior disassembly