Help, please! - Mast step collapsing

Bill Baum

Member I
Ericson 33 – 1982 Keel-stepped mast

Please help me with advice on what I’m going to find on this project – and how to fix it!

Background:
Having read in the past about mast steps sinking, I have had a discipline for years of making a fairly precise measurement each year of the height of the cast aluminum mast step with respect to the cabin sole.
Last year, for the first time, the mast step had sunk 1-2 mm ( about 1/16”).
Upon examination, we noticed that the back to corners of the mast step had snapped off. Then we noticed cracks in the fiberglass underneath the mast step. The aft edge of the wide fiberglass rib upon which the step sits was cracking and sinking.
(This photo shows the wide transverse rib upon which the step sits – it was taken when we were putting in the new floor a few years ago - the step was not yet sinking and we ignored the cracks visible in the wide rib (probably a mistake!))

Mast Step no Floor 2.jpg



This week:
The mast is out of the boat. We removed the four lag bolts and the cast aluminum mast step came off easily – in two pieces – the aft 1” of the step (not just the corners) had been broken off. We immediately noticed what may be the root cause of this whole problem. Underneath the mast step was a smaller rectangle of four open screw holes. I’m thinking that this is not the original mast step (? not the original mast?) and that someone just carelessly put the current step over the old holes without sealing them. So for the last twenty years that we have owned the boat mast water has been leaking down into the rib structure.
(Note: The Rig-Rite catalog photos and measurements indicate that we have a Schaefer mast)

Today:
I had to start somewhere, so today I cut a rectangle of fiberglass out of the step area, cutting exactly between the old, open, screw holes.
I’m not too surprised. There is wood under there, and it is completely soaked. There is a gap – the wood is separated from the underside of the fiberglass, about 1/8” below the bottom of the thick glass. The wood appears to be split, with the aft portion a greater distance below the glass.

IMG_20200418_164944[1].jpg

Overall question:
How do I fix this so that the mast step and mast are solid and secure? ( On the aluminum step itself, I know a good welder who will weld it back together this week)

Questions on the way…
How far does this wood go? How far port/starboard within the wide rib? How deep into the keep stub area?
Can I get the wood out and replace it with something better?
How structural is this port/starboard “wide rib” and how do I make the repair without compromising the structure?

Thank you for any advice and guidance! I know there were only 28 E33’s built, but I am hoping some other models may have a similar keel-stepped structure and other owners may have valuable advice!
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
Not familiar with your particular TAFG, but our mast rests on on a heavily laid up "hat section" that extends out under both settee faces. The "core" under each of these pieces is non-structural rigid foam. Hope that some owners of Ron Holland 33 and 36 designs can weigh in soon.
Good luck,
Loren
 

markvone

Sustaining Member
Hi Bill,

I got your PM.

I have no idea why you have wood anywhere near your TAFG. Perhaps someone on the site has the layup details of the TAFG. I'm pretty sure the TAFG from each model will be similar in layup. You typically use a core between two skins to maintain stiffness while saving weight over a solid fiberglass layup. This makes sense for large areas like the deck or hull skin but would add considerable complexity and expense to the TAFG for very little weight savings.

I've included pictures of the E36RH mast step and the exposed TAFG. You may be able to find a similar picture of the E33RH TAFG in one of the brochures. The E36RH mast step is bolted to an aluminum plate which spans the forward TWO deep TAFG spans over the keel/bilge areas.

MarkIMG_1273.JPGericson 36RH TAFG original photo.jpg
 

Bill Baum

Member I
Mark - Thanks for your reply. The wood I have found is not coring of the TAFG - it is a substantial piece inside the (single) wide rib of the TAFG that the mast step sits on. The half-inch thick section of glass that I cut out in my picture was directly under the aluminum mast step, and probing today with a narrow drill bit I found that the wood underneath is about 3" thick. Under the 3"of wood there is a thin "floor" , then a hollow space of a bilge area. This is all within the wide rib. There is actually a limber hole low in the bilge area just aft of this wide rib which provides access to this hollow space.
We have also found wood in this rib 10" to starboard where there is another limber hole under the floor. (Mark - is there any chance that there is wood in the two ribs that support your metal plate?)

All other port/starboard ribs are hollow with a wall thickness of about 3/16", and all longitudinal ribs are hollow as best I know.

So does anyone know the function of this big piece of wood? If it's structural - ie supporting the mast step, then the question is how I replace it and repair the rib (which now has not only the original cracks but a big rectangle cut out of it). If the wood is not structural then I just need ideas of how to repair the rib.

Thank you for any additional thoughts or experience with this type of construction!
 

markvone

Sustaining Member
Bill,

What type of bolts were holding your mast step to the TAFG? I was thinking that the wood under your TAFG was placed there so that lag screws holding the mast step would have something to thread into. This is similar to the wood inside the engine support section of the TAFG which allows the engine mount lag bolts to bite. See the current thread on Engine Mount Lag Bolt Stripped. The mast step screws just need to hold the step in a fore-aft position so they don't take a large load.

My mast step bolts are machine screws that thread into the aluminum plate not the TAFG. I sheared one and had to drill and tap a new hole. No wood shavings came out when I drilled my mast step TAFG, unlike what I read in the Engine Mount Lag Bolt thread.

I continue to believe that the wood in your TAFG is NOT to support the mast compression load. I assume your mast step TAFG cracks came from freeze - thaw cycles due to the water and wet wood expanding inside the TAFG. You're up near Rochester, NY correct?

I am thinking that repairing this should not be a big deal.

My thoughts:

I would chisel out the wet wood via the square hole as best I could so that it can't expand and crack the TAFG
Dry out the area
Rebuild the cracked edge of the mast step TAFG to level
Add a 3/8 inch thick aluminum plate over the square hole on top of the TAFG, under the mast step (it can over hang the TAFG edge if needed to support the step).
Tap the aluminum plate for the four corner mast step bolts. Use 2-3 inch long bolts that extend into the TAFG so that the mast step and the aluminum plate are "pinned" in place fore-aft and side to side.
Add mast
Go sailing

With any luck, someone here will have dug into the mast step on another model and may have some insights. It may take awhile for them to see this thread. You could also search "mast step" to find other possible threads.

Mark
 

kapnkd

kapnkd
Bill,

What type of bolts were holding your mast step to the TAFG? I was thinking that the wood under your TAFG was placed there so that lag screws holding the mast step would have something to thread into. This is similar to the wood inside the engine support section of the TAFG which allows the engine mount lag bolts to bite. See the current thread on Engine Mount Lag Bolt Stripped. The mast step screws just need to hold the step in a fore-aft position so they don't take a large load.

My mast step bolts are machine screws that thread into the aluminum plate not the TAFG. I sheared one and had to drill and tap a new hole. No wood shavings came out when I drilled my mast step TAFG, unlike what I read in the Engine Mount Lag Bolt thread.

I continue to believe that the wood in your TAFG is NOT to support the mast compression load. I assume your mast step TAFG cracks came from freeze - thaw cycles due to the water and wet wood expanding inside the TAFG. You're up near Rochester, NY correct?

I am thinking that repairing this should not be a big deal.

My thoughts:

I would chisel out the wet wood via the square hole as best I could so that it can't expand and crack the TAFG
Dry out the area
Rebuild the cracked edge of the mast step TAFG to level
Add a 3/8 inch thick aluminum plate over the square hole on top of the TAFG, under the mast step (it can over hang the TAFG edge if needed to support the step).
Tap the aluminum plate for the four corner mast step bolts. Use 2-3 inch long bolts that extend into the TAFG so that the mast step and the aluminum plate are "pinned" in place fore-aft and side to side.
Add mast
Go sailing

With any luck, someone here will have dug into the mast step on another model and may have some insights. It may take awhile for them to see this thread. You could also search "mast step" to find other possible threads.

Mark
(Obviously) The more broadly you can manage to cover the base area of where the mast compression loads come down on a plate, the better off you will be.

Is there anyway you can add a solid piece of aluminum plate above the current plate that better expands the load bearing surface - even if it means shaving said added plate difference off your mast?

Our 32-II is deck stepped but still had very similar compression problems with the cabin sole. From the factory there was a small gap between the compression post and to the keel which ultimately led to the cabin top main brace cracking. Warranty repairs and later our own didn’t work till we sacrificed a bit of room going forward between the main bulkhead in favor of an aluminum pole from cabin top directly to the keel with a 1/4” piece of aluminum channel underneath it.

Probably overkill, but it IS solid now for sure! Dissipate that load over as much area as you can for better piece of mind. As you can see in the photos we dissipated the loads top
and bottom as much as we could.

Luckily we had better access than you have but it looks like you can possibly consider a larger thick plate perhaps?

34AEFE34-7AED-4394-B79B-1B9DA9A56043.jpeg1CBF3770-CEBB-490B-ACA3-611239D1F805.jpeg
 

Bill Baum

Member I
Mark - It is lag bolts which hold the mast step to the rib - and yes, I am very familiar with the wood farther aft within the engine beds. So yes, I could see the argument that the wood is not structural, except that we know the wood extends at least to the starboard 10" within the rib. I had developed the impression that the wood was structural, bridging over the keep bilge and resting on the "shoulders" of the bilge and helping to support the mast. But you may be right.
Your thought of freeze expansion as the cause is also interesting. We owned the boat through 12 Rochester winters with those hidden holes allowing water into the wood. However, for the last eight years we have sailed and stored in the boat in the Caribbean. The first photo was when we changed the floor in Puerto Rico in 2015. There are visible cracks then on the aft wall of the rib, but the damage has progressed in the last five years as the boat has been in the warmth. In the second photo - current - the aft edge of the very thick layup under the mast step is actually broken, there are new cracks in the adjoining top surface of the rib, and the whole area under the mast step has tipped backward. (that why the mast step fractured)
At this point I think there is enough damage that I can't fix it without lifting the floor and getting better access. I'll work on that over the next week or so.
Kapnkd - now that is an impressive job of spreading the load!
I do hope that some other E33 owner chimes in with direct knowledge - unfortunately there are only 28 of these boats and i do not have direct contact with any of the other owners..
BTW, Mark - I think we have exactly the same mast step and mast section. Do you know/agree that it is a Schaefer mast , not the more common Kenyon used by Ericson? Mine is tapered at the top. I see you have the same unusual table that folds up against the mast. In general I like it, but it really isn't stable enough to use while underway...
 

Bill Baum

Member I
I just found this from searching within the forum. It is from a different Ericson model, but the author was cited as a former engineer at Ericson and it makes me think our wood may have been structural. I am not copying it here, but I found the actual Ericson bulletin which went out that described the issue and provided a sketch and procedure to use aluminum "side-plates" to reinforce the rib on older boats...

https://ericsonyachts.org/ie/threads/e35-or-e35-3-grid-beam-cracking.2356/page-2


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.
-Roger
 

Keith Parcells

Sustaining Member
Bill,

wow, this is scary. I have never had the mast out of my boat (hull #24) Nor have I pulled the floorboards up, so I don’t know how much I can add to the conversation.

i would say that I have become a fan of G10 for boat projects and repairs. If you must replace the wooden beam beneath the step, how about considering G10 for the job? Perhaps you could make a G10 transverse piece with aluminum plate over it, as has been suggested. Two layers (Or more) of slightly lighter material might be even stronger and more resistant to future damage.

BTW, have you used (or overused) a backstay tensioner?
 

Pat C.

Member III
I'm sure I remember reading about the wood in the TAFG under the mast elsewhere, and seeing that it is a structural component to compensate for the loads on the spar. Seem to think it was a 4X4 piece of hardwood, don't know what type wood. It does span quite a ways across, only below the mast. I think on later models the wood was replaced with structural foam in later years.

This is just memory on what I've seen either here or elsewhere. For what it's worth.
 

Bill Baum

Member I
Hi, this is Bill, the OP, with an update. Well, there is no question that it was a giant timber, meant to be structural. Approximately 3 1/2" thick, and between 9 and 11" wide (the rib gets wider under the mast step), the timber spans a hollow space where the bilge is deep, and fills the width of the rib right out to the stringers under the settee faces. It was soaked, and the boat has been covered all winter, with the mast out and mast partner sealed. The timber was wet on all surfaces, and was not in contact with the 1/2" glass pad under the mast step. I still am thinking the water intrusion was from the four open, unfilled, screw holes under the current mast step left by someone before we bought the boat 20 years ago.

Most of the timber fell apart and was easy to remove. I've got most of it out and am thinking of how to rebuild. This is a picture of the current state. (The square edge of the wood in the center is only an artifact of my removal method - the timber was continuous, reaching underneath the glass on the left...)
IMG_20200508_112848[1].jpg
Clear failures here are that water got to the wood, the wood lost contact with the top surface of the rib (may not have ever had contact depending on method of installation), and that the rear vertical wall of the rib buckled and cracked. Less clear is why the 1/2" thick glass directly under the mast step cracked. I need to study the removed pieces more carefully. It did crack in a line directly between the two aft lag bolts, may have been a weak area, but there may also be a fault in that section of the layup.

Any repair will include:
- keeping water out of the rib - thinking hanger bolts embedded in solid resin to mount the step.
- thickening the vertical walls of the rib for increased stiffness to prevent buckling (E35 had a this design change after rib buckling)
- providing new support under the thick glass layup which will be recreating for the top surface. Will likely go with hardwood again (rebuild like for like), but coat the wood in epoxy for second layer of water defense, and by laying the new glass over the wood ensure that the mast step benefits from the support of the wood.

More to come!
 

Keith Parcells

Sustaining Member
Bill,

I know you have a lot of work before you get to this point, but when you are ready to begin mast reinstallation, be sure to download the E-33 owners bulletins #1 & 2 from the resources section here at EY.org. Those are invaluable references about installation and tuning, written by Don Kohlmann at the Ericson shop in 1983. For our fractional rigs, the techniques they describe seem essential.
 

markvone

Sustaining Member
Bill,

I would use G10 to replace all the wood. You can glass one inch thick sheets together to make a block as big as you need.
Instead of going out wide to the stringers, can you take the G10 directly down to the hull to take the load? Or some combination of deep and wide G10 sheets to beef the whole area up. No worries about water, so you can go into the bilge, just need to add limber holes as required.

I remember a thread/blog about a young couple on an E39 who replaced the E39 mast support steel beam with a laminated G10 base.

Mark
 

CSMcKillip

Moderator
Moderator
Well.... I am officially back online after a short 5 years on and off the forum. Bill, I will dig thru or photos of when we removed the floor and cleaned the TAFG from all the years of Fuel from the PO. I will also be at our boat this weekend and will look deeper at this area.

Hull 22
 

CSMcKillip

Moderator
Moderator
I spent the night on the boat last night, I didn’t get any good photos do to the wood and trim on my floor is really tight to the mast, but from what I did see- my mast step is completely different. Mine seemed to be below the fiberglass completely, I didn’t see any type of base pad, no bolt heads, nothing. It was about 1/4” thicker then the mast and the glass was molded around it completely.

Chris
 
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