Deck core repair around mast base. Oday 23-2

[cfiles0920]

We have an '84 Oday 23-2, and last summer I noticed that I was having issues keeping the standing rigging tuned. Turns out I have pretty soft core around the mast base and it was compressing quite a lot. (In hindsight, it had pretty bad spider cracking around the mast when we bought it, but being a new sailor, I didn't know any better.) Anyway, being a YouTube mechanic for most of our other vehicle/house issues, I think this is a great opportunity to learn a new skill and repair this myself.
So far, after research, my plan is to cut out the top layer of fiberglass, dig out the wet core and replace it with new balsa. I'm planning on using West System 105 and 206 slow hardener, due to it still being in the mid 90's here in south Alabama. I would like to replace the mast light plug and re-wire to the breaker panel while I have a big hole in the boat. I have tried to search around here for more of a guide or a how to post, but I may just be terrible at searching.
Does anyone have much experience tackling a project like this or can give me any tips/tricks, lessons learned, or while you are in there's that I can use to make this job a little less daunting? I'm in the planning stages now and I am trying to compile a materials list to make this job go as quickly as possible so we can be back in the water by October!

Thanks in advance!

 

[danooxnard]

It sounds like a good plan, but I would not us balsa to recore. I would use g10 a type of fiberglass board the does not rot or compress. You hopefully wont need much you can find pieces on ebay and other sites. I am sure you will get lots of good ideas on this. there have been many good post on things like this.

 

[Don S/V ILLusion]

Is this the bulkhead placement of your boat?

if so, you are a few steps ahead of yourself.

The mast step won’t depress unless the bulkhead gave way, the mast post sank or the base of the post rotted away, all of which and structural issues which need to be addressed before dealing with a cosmetic issue like the step area.

 

[Project_Mayhem]

I've done this exact repair and rewire on my O'day 25. I'll try to write up some info tomorrow. Dont be afraid to bug me if I forget

 

[cfiles0920]

Is this the bulkhead placement of your boat?
View attachment 234201
if so, you are a few steps ahead of yourself.

The mast step won’t depress unless the bulkhead gave way, the mast post sank or the base of the post rotted away, all of which and structural issues which need to be addressed before dealing with a cosmetic issue like the step area.

So I jumped in and snapped some photos of the compression post. The bottom of the post on the sole does seem a little deteriorated at the foot, but most of it seems intact. Underneath the cabin sole i am not sure what is there. It seems like 2 2x4's sandwiched that run forward farther than i can reach. It doesn't feel rotten, the best I could describe it is hollow. Maybe fiberglass wrapped rotten wood? What was there from the factory?

 

[Don S/V ILLusion]

Don’t know th design and construction materials originally so can’t help. also can’t tell hat the base of the mast post at the keel is but looks like glass encapsulated wood - worth checking.
The only certainty is the deck area around the mast step doesn’t sink except when something supporting it fails.

 

[Project_Mayhem]

Are you looking to repair the area above the compression post or below?

 

[Don S/V ILLusion]

Are you looking to repair the area above the compression post or below?

Think he is trying to determine where the problem is first.

 

[Project_Mayhem]

I think the easiest and most accurate way to determine if the mast step (between the step and compression post) is compromised is to take a 3/4" core sample. Remove the step, drill out just enough to remove the fiberglass skin, dig a little deeper into the wood as necessary and if it's good, fill it back in with thickened and/or reinforced resin. If you can't get a finger in the hole, you can't feel if its wet. What comes out on a small drill bit is not enough to determine the condition with much accuracy in my experience

 

[cfiles0920]

I definitely want to figure out what the exact problem is. I'm pretty sure the balsa under the mast step is wet/rotten due to the tap test I have done in the area, but physically verifying is probably a better idea. I still want to rewire the mast and repair all the cracking around the step, but after posting here and getting a few answers, it seems like I need to ensure the structural integrity of the boat from the keel up first. BUT I would still like any advice you may have about re-coring and re wiring the mast plug!!

 

[Don S/V ILLusion]

……. f I would still like any advice you may have about re-coring and re wiring the mast plug!!

Not sure what you mean by “mast plug”.

 

[cfiles0920]

Not sure what you mean by “mast plug”.

The through deck power connector next to the mast base for the steaming light. I'd also like to add an anchor light, even though (if I recall correctly), a boat my size is not required to have.

 

[Don S/V ILLusion]

As you have to rebuild the mast step anyway, why not eliminate another hole in the deck for running wires and just run them directly into the cabin so the connectors will be out of the weather ?

 

[Project_Mayhem]

As you have to rebuild the mast step anyway, why not eliminate another hole in the deck for running wires and just run them directly into the cabin so the connectors will be out of the weather ?

It's doable but it would require a fair amount of work in the O'Day

 

[cfiles0920]

Is it a good idea to run wires directly into the cabin if I plan on taking the mast down to pull the boat out of the water once or twice a year? Honestly I really want to make these repairs and get back sailing ASAP.

If the sole of the boat under the compression post is not sunken, or flexing at all under bodyweight, would you say that it is solid and not in need of repair? I may take a drill bit and check for wet material inside the glassed in stringers.

 

[Project_Mayhem]

Stringers are the support built into the side and bottoms of hulls. My O25 had a single, hollow, fiberglass stringer on either side of the hull. The hull still flexed when the boat was pushed up against the dock in the waves.

When I dug into my mast step I found much more rotted material in the area around it. I opted to repair an inch or two around the area with thickened resin for strength and to seal off the new plywood I was installing. The deck and cabin top still had plenty of strength and I didn't want to turn it into a giant project.I replaced the mast connector with the one below. I surprised at how robust it was. PS has some reviews of connectors here

As for the repair itself, I only cut out the area closest to the step to minimize gelcoat repairs. I matched it as best I could. I didn't paint it on or spray it. I literally poured it on, let it cure and then sanded it down. Nobody could tell unless I pointed it out. With the expectation that my repairs would be far from perfect, I installed a mast block plate. It helped hide defects and allowed me to run my main halyard to the cockpit.

Read West System's fiberglass manual. It's literally the bible of fiberglass repair. Boatworks Today is also an outstanding resource