How can I fix this rotten mahogany cabin wall?

I’m not familiar with your local weather conditions, but if it’s at all rainy, your first priority will be to keep the wood dry.
Build a waterproof temporary shelter over the boat.
Don’t move onto the boat, this will be counterproductive. You need room to work, store materials and tools, make dust, and mess with smelly chemicals.
Working around your (and your girlfriends) personal “stuff”, and keeping it clean is a pain, possibly resulting in incomplete repairs or half hearted attempts.

 

You are beyond scarf repairs.

Replace the whole window wall!

 

I've been waiting for that Bluenarr. I just didn't want to be the first one to say it.

The next question I'd have is what's holding up the cabin sides and what about the windshield area and the aft cabin support. That's just the opening bid.

Those photos bring back memories of "Pearl" in the early 2000's. You know what happened to her cabin and decks, right? Landfill.

This has huge project written all over it.

Pretty boat. Landfish, how much time, effort and money are you willing to put into this?

 

Ive got to say that the obvious rot is probably a small indicator of that which is hidden from immediate view.
She is certainly pretty, but like a beautiful woman, that fact can blind you from other flaws!

 

The cabin side doesn't even need a scarf joint. A simple butt join with epoxy is all that is needed. It won't look as nice as a full replacement, but certainly would be acceptable versus a foamy mess.

 

Thats the first thing we did. There is a temporary tarp shelter covering the whole boat.

Do you have any pictures from your project? And how much you spent on it?

We have a repair budget of 5k usd for this boat.

I want to know as much as possible about the scope of this boat, where should I look for more damage?

So which is it? Can I get away with only replacing the top part?

 

Screw plywood over the hole, that's the temporary repair.
For a permanent repair done in place you would have to strip plank the hole.
5k USD is nothing for this kind of boat, even if you were a professional wooden boatbuilder. If this thing is to be just another ugly floating shed without indoor plumbing that goes nowhere, then it's possible to do something with that money that will keep it from sinking over the winter, while the inhabitants are more or less reasonably dry inside.

 

What is a realistic amount of money needed for this kind of boat?

There is no hole in the hull, why do you think it would sink? Is it from rain going into the hole?

 

The budget depends on what you want and the current condition. It's impossible to put a price on it from a distance. Everyones standards and expectations are different. In my opinion 5k will see you over the winter, and that's as far as I am willing to go.

Of course there is no hole in the hull, otherwise you would be already sinking. That does not mean you don't have hidden problems.

 

Oh boy.......Landfish you asked about costs and pictures.

Briefly, my boat is much smaller than yours. About 1/2 the size at 25 feet. I'll post a link to the first post I ever made here in 2007. There are some photos there that will give you an idea of what I faced.
Old boat, new life..... https://www.boatdesign.net/threads/old-boat-new-life.18865/

Some seven years later I had her finished enough to put her back in the water. She wasn't nearly done but she was "good enough" at that time.
Missinginaction's restored 1973 Silverton launches Monday, August 4, 2014 https://www.boatdesign.net/threads/missinginactions-restored-1973-silverton-launches-monday-august-4-2014.51071/

This year she looks like this.....



As for costs, I wrote a post a little while ago. it might scare you but remember I did a complete top to bottom restoration and made a lot of improvements to this boat. Probably too many but that's debatable.
Want to know how much a restoration might cost you? Read on..... https://www.boatdesign.net/threads/want-to-know-how-much-a-restoration-might-cost-you-read-on.62104/

If I were you I'd cover it and take a step back and think about this whole project. $5,000 USD is a decent chunk of money. That said you'll need considerably more depending on how far you want to go with this. You also need to consider your time. Finally "Pearl" has a robust fiberglass hull so, aside from stringer and floor/bulkhead rebuilding I didn't have the issue of wood there.

Good Luck. Think. Plan. You may decide to go forward with this. Don't be afraid to admit that this was a mistake though. There is such a thing as cutting your losses.

MIA

 

Much ado.

Just get a utility knife and some cardboard and a straightedge.

Draw a line flat across the removed area.

Cut it away.

If it includes the window, remove the window and template the opening with cardboard.

Then make a template of the piece of mahogany.

Go find the right thickness material. 3cm is an odd dimension here in the usa. We have 4/4=0.75",5/4=1",.6/4=1 5/16" ...the 6/4 is the closest to your 3cm.

Here is a vendor. When you order lumber, find out how much you can get for the freight bill. The freight will cost several hundred dollars, so buy an assortment of thicknesses that you may need elsewhere.

6/4 African Ribbon Mahogany Lumber, Shipped from Florida https://buy.advantagelumber.com/products/6-4-african-ribbon-mahogany-lumber-fl

Once you get the lumber (which you should already have if you are cutting her up), sand the join surface flat. Cut the new piece and dry fit it.

Mix a wee bit of clear epoxy and paint the joining edges of both boat and board with it. Wait about 30 minutes. Mix up some epoxy pb. I prefer cabosil and epoxy about 1:10 by weight or about 2.1-2.2 cab to epoxy by volume. You don't want sawdust here, but you can use wood flour.

The area of the join can be masked off with some 7 day release tape.

Apply epoxy to both sides, youonly need 1/16" or so.

Bond the pieces together.

You need some mechanical means to keep the board from sliding off a bit.

I like to clamp sticks covered in ship tape, but remove the excess epoxy and masking tape first.

Then wait a day.

Also in your budget, you are going to want some type of caulk you use as a go to. I don't have a recommendation, but do not use silicone and avoid clears. Some caulk that matches the mahogany.

After you do the repair as a strip repair, some day in the future, you may decide you want to replace the entire section for looks. By that time, you'll be ready.

I'd say you'll burn up close to a grand buying some materials for this repair. Epoxy shelfs well; get a gallon and a half. The mahogany should cost say 3-500 to ship unless you can source it, so you'll want to spend 3-500 on product to reduce shipping per piece. Unless you can find a local vendor and spend a couple hundred on various thicknesses. A boat like that will need to stock some.

But you need all the other stuff. A bucket of cabosil, gloves, n95 masks (do not whiff cabosil), mixing pails, weigh scale, masking tape, plastic to work on, shipping tape for release material, sanding foam block for hook n loop, sandpapers 40-60 grit for shaping, 120 grit for sanding the epoxy off the board when you get a bit on it,

 

Landfill
You ask about price. A decade or so ago, I partnered in a similar project. Original purchase was the loose change in our pocket. We weren't willing to ante up a full dollar. A year later we sold it for $45k. With $5k profit split three ways as wages.


There is rot all across the top horizontal, rot in the bottom horizontal and evidence of rot the the top tennon of the vertical. Replace the whole thing.
The roof beams have rotten ends- replace a foot of each.
Look for rot under that window. I'll bet dollars to donut that the floor is compromised.

 

So the investment was about $30,000 you cleared $15,000 and split that three ways. Right?

I'll bet you had tools blueknarr. Some experience as well? When I did my boat I had a hardwood supplier down the road, actually on the way to the boat club from home. Drove over to Boulter Plywood in Boston for my BS1088 ply. Never had to have anything shipped. BS 1088 12mm Okume was $80 a sheet in 2007. Most places want you to call for pricing today as the market moves so fast.

My "hardwood" of choice was philippine mahogany. It was running between $4 and $7 a board foot. As I recall my System Three Resin was in the area of $50 a gallon back in 2007. I see someone writing above about buying 1-1/2 gallons. I used to buy mine in 5 gallon jugs and I used every bit. Big differences between a decade ago and today's prices.

 

You need to remove the window, interior trim, etc. and get rid of all the rotted wood. The random shapes you are cutting would require a very skilled finish carpenter to get a proper fit. Further, the bevel is too short. You need at least 5 to 1 ratio for epoxy. However, there will most likely be a lot more damage and problems. For example, the rivets and screws on the planking are likely corroded considering the age of the boat. Your best route is to get a surveyor knowledgeable on wooden boats or a wooden shipwright to survey it and give an honest opinion. Digging at small areas is a waste of time if there are major structural problem that will make you remove the repair you just did to fix them.

 

No $40,000 invested
$5.000 split three ways.

One partner owned a boatyard so no harlots fees.
Other partner a deisel mechanic .
I worked at a cabinet shop.

Lots of collective skills and tools. Minimal expense other than supplies.