Olson 34 Mast Step Construction

[mschrager]

Wood Riser Replacement under Mast Step

Re-visiting this thread as we are in process of doing new floors as well - and this seemed like the right forum to add to.

One question in reference to Loren's note on the floor risers"The wood risers on that one hat do show a tiny bit of cracking along their resin interface with the hat stringer. Those thin risers have no structural function, and exist only to give the sole screws something flat and uniform to bite into."

We found many to be rotten, and decided that rotten wood = no good. Considering replacing with a longer term spacer like G10. Any recommendations on what to go with that may be a bit easier on the wallet?

Also, around the mast step found the risers to be rotten where they extend underneath the mast. My Ercison 35-2 buddy thinks these may in fact be somewhat structural, but after reading through here, I am not so sure. Anyone else find this when redoing the floors/spacers?

Cheers,
Mike
S/V Razzberries

 

[Drewm3i]

Wood Riser Replacement under Mast Step

Re-visiting this thread as we are in process of doing new floors as well - and this seemed like the right forum to add to.

One question in reference to Loren's note on the floor risers"The wood risers on that one hat do show a tiny bit of cracking along their resin interface with the hat stringer. Those thin risers have no structural function, and exist only to give the sole screws something flat and uniform to bite into."

We found many to be rotten, and decided that rotten wood = no good. Considering replacing with a longer term spacer like G10. Any recommendations on what to go with that may be a bit easier on the wallet?

Also, around the mast step found the risers to be rotten where they extend underneath the mast. My Ercison 35-2 buddy thinks these may in fact be somewhat structural, but after reading through here, I am not so sure. Anyone else find this when redoing the floors/spacers?

Cheers,
Mike
S/V RazzberriesView attachment 54374View attachment 54373View attachment 54372

Does this boat have a TAFG? Doesn't look like it as there isn't usually exposed wood in a TAFG. I'm not even sure there is encapsulated wood in the mast step on most TAFG boats (do you guys know?)--pretty sure the core material used in the mast step of most 80s Ericson's is a closed-cell foam, but could be wrong on that.

From the pictures, it's hard to tell but everything under the mast step would be structural IMO--needed to take/transfer compression loads into the keep which is then bolted and held upwards against the hull. Without proper support, the mast would want to push through the boat into the keel stub and joint. I would absolutely rebuild it back how it was with the assumption that the designers had a rhyme or reason for doing so.

 

[Loren Beach]

There is no separate wooden riser under our mast step (hull #8). As noted in a past thread the Kenyon cast aluminum base is lagged down to a rather thick heavy duty FRP 'hat stringer' that reaches out under the fronts of opposing settee moldings.
As for a TAFG, the O-34 has an extensive lower interior molding that carries the inside strength from bow almost to stern, and carries the engine bed loads too. It's kind of an engineering relative to the Ericson Grid which extends all the way to the transom in many models. It is a highly-detailed piece of glass work, IMHO. Like the hull mold, the thickness varies with the predicted loads calculated, area to area.

 

[Slick470]

On our 911, a number of the wood risers needed replacement when we had the sole out to refinish it. Ended up using 1/4" (I think) PVC siding cut into strips that were the same width as the wood and then epoxied them to the stringers. Followed some West System guidance about flame treating the PVC to help with the epoxy bonding. They've stayed put for a few years now, so it must have worked.

 

[mschrager]

We have the Ballenger Spar and the setup sounds similar to your 911 Andy. Looking at G10 strips on McMaster Carr at reasonable prices so we may go that route, and do some simple attachment as these dont seem structural.

Our's also seem 1/4" in comparison to the 1/2" needed to replace the wood risers further aft.

Will post more as we continue the project!

 

[mschrager]

Routed Edge on the O34 Floorboards

Alrighty, we have made new wood risers of out king starboard and have tacked them down to make a nice new flat surface for our new boards. Got the new boards all cut out with a tracer bit.

We are trying to replicate the rounded edge that matches the fiberglass molding. Doing some research we think we need a thumbnail bit. Curious if anyone has rebuilt their boards and could recommend the router bit needed to replicate the exact edge?

 

[Loren Beach]

Lucky us - we were able to restore the dirty surface of the original sole pieces. New T&H plywood was quite expensive, way back then, and likely same or worse now.
That bottom edge does have a sort of rounded shape that fits the flanges in the fiberglass interior molding.
If you are starting over I would suggest partitioning that large aft sole piece into three sections, with a lift-out center part that matches the width and trims of the ones already there, forward of it. That way you can clean out the large hull section and paint or gel coat it. There is a nifty/easy way to steady the port aft corner, by the head door, with a small frp piece underneath, also. PM me for more info about that.

As for the "risers", any solid wood should do fine since they are just there to screw the sole pieces onto.

I wonder how you managed to glue the "king starboard" down? I have found that almost nothing really sticks to that material!

Aside: if you copy my method of steadying the table with the mast slot, this will much improve the strength of it, over the factory way to bolting only to the sole. I have a picture of that small project. https://ericsonyachts.org/ie/ubs/o-34-table-bolt-down-and-front-brace.581/

 

[mschrager]

Great thought Loren on breaking out the aft section into 3 boards - hadn't thought of that. Will look into it. Very curious on steadying that aft corner - I will shoot you a PM.

For the Starboard, I used double stick tape to hold them in temporarily with the old floorboards. This will allow us to race next weekend and take some time to refinish the new Teak and Holly appropriately. The boards themselves came to just about $1K for the amount of material needed. Not fun, but needed as the old boards were completely shot.

We will keep the group posted if we find the right router bit. If anyone knows, please let me know!