Mast Step Material

[Nick J]

With all the work I've put into the rig this winter, I thought it would be prudent to look at the mast step before I put it all back together. Now I'm kind of regretting that decision (ignorance is bliss?!). It looks like the mast has been cut down by about an inch at some point in the history of the boat and the step was built back up with a shim. I'm assuming its something similar to King Starboard. I cut a small piece off to help identify it and here's what I found:

• Easy to shave a slice using a ceramic knife
  • Somewhat soft
• sinks in water
  • More dense than King Starboard / polyethylene
• smells like candle wax, slow burn that continued when the flame was removed, and had a blue flame with orange tip when burned
  • Indicates it's in the Polyolefin family (Polyethylene, poly propylene, etc)
  • Most polyolefin don't have great compressive strength
• Dark Gray in color

Although the mast step has been in place for a long time, I'm apprehensive about putting the rig back together on a material that may not be up to the task. I'm wondering if this has had an affect on rig tension. I may be overthinking this, but on multiple occasions, the rig seemed to be looser under load than at the dock (more so than I would expect).

If I do go down the path of replacing this block, the 8 screws attaching the plate to the TAFG and the 4 bolts attaching the step to the plate are completely seized in place and will probably need to be drilled out or cut through the block.

Does anyone else have experience with this kind of issue?

 

[Kenneth K]

Yeah, tough call. Also, on the four bolts (per side) on the flat plate, I wonder if those are just lagged into the TAFG, or if there is another plate or individual nuts on the bottom side. If so, can you access those nuts?

You could try to math it all out and see what you get: if you know the compression strength of polyolefin, figure out the surface area of that oval base. Then use all your Loos gauge settings (% of breaking strength of the cables) to figure out the tension on each shroud/stay and add them all up. This will tell you what kind of PSI load the base is under. If you're below the compression strength by enough margin, leaving it alone could save you a lot of time. Also if the shim were failure failing under compression, I think you'd see signs of bulging, cracking, disfiguring in the sides of the base. I can't see that in your pictures.

 

[Prairie Schooner]

Nick,
Strictly in the FWIW department, some pics of our step when the mast was out in 2022.





Sorry, no help on the material science front.

Jeff

(those wire nuts are long gone)

 

[Nick J]

Good idea @Kenneth K

It's been a long time since I've done anything like this and I'm probably missing something. At the end of the day, it looks like I would only need to tune less than 1/1000 of an inch out of the system after a year, so maybe this is a non issue?

Stay	Size	Breaking Strength	Safe Working Load	% of Breaking Strength	Load	Vertical component	Corrected Load	Qty	Total Load
Lowers	1/4	6900	1380	12.00%	1380	1	1380​	4	5,520.0
Intermediate	7/32	5350	1380	15.00%	1070	1	1070​	2	2,140.0
Uppers	9/32	9261	1850	20.00%	1852.2	1	1852.2​	2	3,704.4
Backstay	9/32	9261	1850	20.00%	1852.2	0.955779009	1770.29388​	1	1,770.3
Forestay	9/32	9261	1850	20.00%	1852.2	0.94576558	1751.747007​	1	1,751.7

Total Force	14,886.4​
Safety Factor (catch all)	80.00%​
Total W/ Safety	18,608.1​
Mast Area	27.5​
load PSI	676.2​
Compression Strain	0.085500%​
Block Thickness	1​
compression	0.000855​
Creep 1 Year	0.094300%​
Creep 1 Year Distance	0.000943​

It still doesn't seem right to have a relatively soft plastic in the overall system, especially in the critical mast step location, but if these numbers are in the ballpark, it seems OK. Anyone have any input or thoughts?

@Prairie Schooner, I'm envious of your adjustable mast step. That looks like something the rigger would appreciate as well

 

[Christian Williams]

The thing seems to have been there a long time and to work fine.

If that's true, it would be good enough for me. Avoids can-of-worms effect.

 

[Nick J]

The thing seems to have been there a long time and to work fine.

If that's true, it would be good enough for me. Avoids can-of-worms effect.

I like your thinking. I need to work on adopting that from the beginning.

 

[Kenneth K]

It still doesn't seem right to have a relatively soft plastic in the overall system, especially in the critical mast step location, but if these numbers are in the ballpark, it seems OK. Anyone have any input or thoughts?

Yeah, that's a great chart.

I was thinking in even simpler terms: If the mast exerts 15K pounds on a 27.5" base, that's 545 psi. As long as the base material has a compressive strength of, say, 3-4 times that (for safety/wear factors), or 1650-2200psi, I don't think you have anything to worry about.

Another consideration is that I don't think most of us tighten our rigging up to the safe working load limit. When I took Loos gauge measurements of my rig before disassembling, most of my readings were at 6-10% of breaking strength. That would reduce the load you calculated by about 50%.

Yeah, PSI is a funny concept. I ran through the same types of calcs when considering keel bolt torque. A single 1" keel bolt exerts 15,000 lb of force at 250 ft-lb of torque, and 21,000 lb at 350 ft-lb. Fiberglass has a compressive strength in the neighborhood of 20K psi. It's the washers (backing plates) that make all the difference: By spreading the load out over 3.2 sq. inches, they cut the compressive force down to 4700-6500 psi, which then yields a safety factor of 4.2-3.0 for the fiberglass.

OTOH (and, don't hate me for this), if that base material is soft plastic, and you have good access with a reciprocating sawblade, it's probably not more than 30 minutes work to cut through the whole slab and the 4 bolts horizontally.


If there are 4 nuts below those bolts, they'll drop out easily, but if the bolts are threaded into the plate itself, you'll still have some work to do to free them.

 

[Kenneth K]

Might be even easier to just put a metal-cutting blade on an oscillating saw. Plunge it into the plastic just deep enough to cut the bolts, directly below the mast step. Then pry the mast step and the plastic off. Bend the protruding bolt ends into an L-shape and twist them off with an adjustable wrench.

There, now you can hate me if I gave you a new project.

 

[Nick J]

We're thinking along the same lines and it's good to hear the feedback. Calculating the loads is also an interesting problem to think through, although a little humbling.

I'm concerned about not being able to get the studs out of the plate after they're cut. With the lag screws stuck as well, I won't be able to remove it and will be stuck with nowhere to put the mast until I get it resolved (the proverbial can of worms) . It's tempting on paper though... I think I even have enough spare G10 available. I'll have to give this one a little more thought.

 

[Kenneth K]

Not trying to talk you into removing the block, as it seems years of use and a few, quick calculations show it's likely up to the task.

But, just to continue with the thought experiment.... I wouldn't want to mess with the bolts lagged into the TAFG--too time consuming if anything goes wrong. But the four bolts on the step itself: If they can't be unscrewed from the plate after they're cut, it seems they could be cut off flush to the plate and new holes could be re-drilled.
.

I don't see the need for countersunk flathead bolts. I'd probably replace with hex-heads and lock washers. Also, probably no need to tap threads into the plate as it looks like there's access for nuts from below. Although, I can't tell from the photos if that aft bolt is open below, or if it sits above the TAFG. Also, it may be better to NOT put a hex-head in front of the drain slot where it might trap debris.

I'd also consider the re-drilling patterns if only 1, 2, or 3 of the original bolts can't be removed from the plate. Maybe also fill any unused holes with epoxy so they don't trap water.

 

[tenders]

Under the Chesterton's Fence philosophy, which I think I heard about here from Christian and have turned into my mantra, I would NOT assume on the basis of a hunch and a sniff that whoever did that was ignorant of the materials used. For three reasons:
- the work is very deliberate, not casually machined or installed;
- it is not showing signs of failure - all rigs stretch a bit under load;
- it has been there for quite some time.

It may not be ideal but it is certainly good enough.

 

[Nick J]

Curiosity got the best of me. It turns out "stuck" and "seized", at least for me, are relative terms. In this case, they're relative to how much torque i was willing/able to apply. I had so much luck with the manual impact screwdriver on the mast, that I went strait to it when a regular screw driver didn't work. And when they still didn't budge, I assumed the fasteners were stuck. It turns out, they just needed a longer leaver arm. I'm assuming the compression of the plastic spacer applied friction to the screws. It also absorbed the impact of the impact screwdriver. It was slow going, but I got almost everyone out. The last one was just connecting the plate to the spacer, so it wasn't necessary to remove.







I found the spacer was compressed and showing signs of significant stress with the sides bowed out and some cracks around the edges. Does this mean it was going to fail or make properly tensioning the rig difficult? I still don't know. I'm convinced this is high density polyethylene and according to the crude math above, it should be OK. I did the buoyancy test again and found the spacer floats in water. I'm not sure why the sample didn't.





I'm assuming one of the previous owners had some issues with corrosion at the mast step. It looks like they fixed it by cutting the damaged bottom section of the mast off, replacing the step, and making up the difference with the spacer. The original 4 holes used to secure the original mast step are there and I don't' see why Ericson would have fabricated their own step when Kenyon made one for this mast section.



I think I'll clean up the step and replace the spacer with G10, but I'm not sure what do do with the 1/2" plate. It has some pitting up to 1/8" deep in a few spots. It still seems solid and I'm sure I can fill the pitting with a high strength epoxy filler. On the other hand, its a fairly easy piece to either fab up myself using standard shop tools or have a machine shop knock it out.

 

[Loren Beach]

If you decided to machine a new aluminum plate for the mast step, I would recommend you have it "Hard Coat Anodized" rather than just primed/painted. This is a more durable surface, and more so than on basic "anodized aluminum".
When our new engine required two machined aluminum riser bars on the original frp bed logs and we saw that the new Betamarine engine came with a cast aluminum exhaust riser, all were sent out for Hard Coat Anodizing. The machinist explained that this would greatly reduce/stop corrosion. From a quick search on-line, this would provide a better protective surface.

 

[nukey99]

All of this is very interesting to read, but it leads to a question about our E35-3, when rain get's into the mast via the various openings, where does it drain out to, what is the opening? I was at our boat today with on of the standard PNW all day rains. While aboard, I could hear dripping, and my ear led me straight to the mast.

I am meticulous about my bilge, so when water come in, it gets vacuumed out and sent to the great water beside the boat. I've been around the mast base and didn't identify any openings in the extrusion, so it has to be coming out the base somewhere. I'm obsessively looking for maintenance points!

 

[Loren Beach]

I've been around the mast base and didn't identify any openings in the extrusion, so it has to be coming out the base somewhere.

Our '88 boat has a Kenyon spar, so some things might not be the same, but I betcha EY tended to follow a standard procedure to keep the training for assembly crews as simple as possible.
We have a notch at the rear base of the extrusion, where the rain water drains into our bilge. In the winter I try to get down to the boat weekly and remove the accumulated water with a "turkey baster". What with double spreaders and lots of halyards entrances/exits, rain gets inside the spar easily. At least it's clean and fresh water!

 

[Christian Williams]

The notch can be rather small and hard to locate.

 

[ConchyDug]

Slap an Enerpac ram under the mast where the spacer was and you'll have the same rig tunability as a Melges 32. Kidding... sort of.

Couldn't you just replace the aluminum with a thicker plate of G10?

 

[Nick J]

Here's some additional threads that are somewhat related:

1984 Ericson 35 III bulkhead and mast step

I'm a new member and presently searching for a sailboat in the 35' range. I've located a 1984 Ericson III which seems to need a lot of TLC, but my surveyor found that the bulkhead which separates the salon and head, and the ajoining bulkhead on the opposite side of the salon were both pulled...

ericsonyachts.org

E35 or E35-3 Grid/Beam Cracking?

Here's something interesting: I just got this email from an owner - who asked about an apparent warranty issue with (what appears to be) the grid cracking beneath the mast. Their email: -------------------------------------------------------------------------------- From: Hoey...

ericsonyachts.org

These posts raise some concern and questions about the integrity of the TAFG on 35-3s, but I don't see any signs of deflection, rot, or delamination in the beams on my boat, so I'm going to stick with the original design.

I'm going to replace the 1/2" aluminum plate. It doesn't look too difficult as long as I get a blank cut to size. I should be able to accurately drill all the holes. There's a couple metal stores around me and a ton online. I'm going to go with 7075 and have it anodized just like the u-bolt backing plates I had made recently. Replacing the plate with G10 would require a thicker piece and that wouldn't fit under the cabin sole without routing out the bottom of the sole.

I ordered a 2" block of G10 to replace the HDPE spacer and aluminum large mast profile piece and a 3/4" block to replace the smaller mast profile plug. I'm going to try to machine small radial channels in the larger G10 base that slope towards a drain hole and direct the water forward to be collected by the shower bilge. Hopefully that will keep mast water out of the main bilge. The current configuration didn't have a dedicated weep hole so mast water just seeped out around the base of the mast.

 

[Nick J]

These posts raise some concern and questions about the integrity of the TAFG on 35-3s, but I don't see any signs of deflection, rot, or delamination in the beams on my boat, so I'm going to stick with the original design.

Once again curiosity got me. This morning, when I was reading through the posts about the cracked TAFG mast step, I didn't believe there would be a block of wood in the beam. My 25+ relied on a block of wood that ended up rotting and caused the compression post to sag. I didn't want to believe Ericson would do the same on the newer 35-3 design. @Roger 's post is what got me thinking. It's good enough to quote:

"Some possible insight on the E-35-3 mast beam. A large block of wood was installed in the center portion of the beam. The wood itself was capable of handling the compression load of the mast; however, there were occasionally voids between the top of the wood and the underside of the beam and/or between the bottom of the wood and the hull. The beam itself wasn't capable of carrying the compressive loads and would collapse until the void disappeared. Of course, rotting of the wood block over time could have the same effect.

A design upgrade, implemented sometime in the mid 80's, was to add several layers of unidirectional glass fore-and-aft to the center of the beam to make it strong enough to support the mast without the wood, although the wood was still installed as a backup. This may be the best repair for beams that have collapsed. For those who might want to take preventative measures, the side plates as described about sound like a good solution."

My boat is an 84 and there's accounts of older and newer 35-3s having the same structural issue. I'm not sure why our boat hasn't experienced any issues yet. It could be that the TAFG was built on a day where they paid extra special close attention and it's up to the task of taking the load or the wood is still intact even though it doesn't touch the top of the keel sump. It could also be because the previous owners didn't tension the rig, sail it hard, or stress it in difficult seas. regardless of the reason, now that we have everything torn apart, I think it's best to take Roger's advise and "take preventative measures". I'll add some extra pieces of G10 to my order and tack on a few more days to the project. What's time anyway?

 

[Kenneth K]

Looks like you've got 4 holes drilled into the plate that also penetrate the beam:

If any of these leaked in the past, it might have let water get into the wood. When you pull the plate, have you considered enlarging these holes a bit to see if you find wet or dry wood? That might tell you a lot about the condition of the wood beam.

If it's dry, just refill the the holes you drill with thickened epoxy. The top of the beam is in compression, so drilling/filling holes shouldn't weaken it much (unlike the case if it were in tension). Also, have you tapped around the beam to listen for void spots? Any voids between the wood (if dry) and the TAFG could be filled with thickened epoxy.

Also, when you put things back together, you could consider NOT using any of the mounting holes above the TAFG beam. Those are just a source for future leaks. The mast step probably doesn't have much of a side-load on it, so the front 2-3 bolts would probably be enough to securely mount it in place. Or, make the G-10 riser base longer so it extends slightly aft of the step, mount the step to the bottom of the G-10 riser base (independent of the plate) , then mount the G-10 riser base to the plate. That way, the aft holes that mount be G-10 riser base to the plate will bridge (but not penetrate) the TAFG beam.