Dyer Dhow Rehab

Ajax

Super Anarchist
14,507
2,801
Edgewater, MD
On to more pleasant business:

I was going to put this in Dinghy Anarchy but a review of topics there indicates that it's really "Racing/foiling Dinghy Anarchy."  The Cruisers are the self-reliant, skilled bunch so I'm posting it here. This week, I'll post photos of the rotted wooden gunwale rail and outline my plans. You guys can offer clever help like pointing and saying things such as "You're doing it wrong."

It also appears that the fasteners to the bronze straps that connect the thwarts to the hull are loose. All of this makes the hull kind of floppy. I can't tell if the bronze straps are weak and need replacement, or if I just need to snug up these fasteners. Another issue is that I'd like to attach bridle lifting points for launch and recovery from the foredeck and I'd like ideas on what/how/where to attach them so I don't ruin the aesthetic of the boat.

For the gunwale rail, I've been presented with 2 schools of thought: 

1. Laminate thin battens and epoxy them to the boat until I achieve a rail of the desired thickness

2. Steam the necessary lengths of wood and rapidly clamp them to the hull and rivet them with copper rivets in the original Dyer method.

I would really prefer option #2. I want to experience this method. I understand that #1 might be easier, cheaper or might last longer.

I'm also hoping to revive the green hull paint. If I can't, I'll strip it and paint it again.

 

The Q

Super Anarchist
On to more pleasant business:

I was going to put this in Dinghy Anarchy but a review of topics there indicates that it's really "Racing/foiling Dinghy Anarchy."  
I ignored that, so I've been putting details of a 1/2 ton 16ft Mini open keel boat in there..

Well, at the clubs I sail, at anything under 17.5ft has to race with the dinghies..

 

valcour

Member
378
90
Ajax,

Steambending is really fun, especially in a straightforward and accessible location like the rails.  You may be able to get away with just steaming the forward ends of the rails to take the bend at the bow. 

You can make a simple steam box for long, narrow stock using 4” PVC pipe.  For steam generation, rent a wallpaper steamer (or buy a cheap $45 one).

 

SemiSalt

Super Anarchist
7,732
261
WLIS
Time to research the properties of various types of wood. 

Oak is the easiest to bend after steaming, but its difficult to laminate since it's hard to glue. Or maybe that's just something I read before epoxy became ubiquitous. 

My only experience stream bending was with Phillipine mahogany. I used a length of downspout wrapped with newspaper as a steam box and a rented wallpaper steamer as a steam source.

I was doing chine logs for a plywood boat.  I nailed blocks on a handy bit of unfinished floor so that I could bend the hot stick in the 2" direction and leave it to cool. Circa 1973.

 
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Ajax

Super Anarchist
14,507
2,801
Edgewater, MD
Time to research the properties of various types of wood. 

Oak is the easiest to bend after steaming, but its difficult to laminate since it's hard to glue. Or maybe that's just something I read before epoxy became ubiquitous. 

My only experience stream bending was with Phillipine mahogany. I used a length of downspout wrapped with newspaper as a steam box and a rented wallpaper steamer as a steam source.

I was doing chine logs for a plywood boat.  I nailed blocks on a handy bit of unfinished floor so that I could bend the hot stick in the 2" direction and leave it to cool. Circa 1973.
Semi, what's good for rot resistance?

 
Ajax...I rebuilt my Dhow a few years go.   PM me and I can share my learnings.

Dyer Dhow.jpg

 

2airishuman

Anarchist
It also appears that the fasteners to the bronze straps that connect the thwarts to the hull are loose. All of this makes the hull kind of floppy. I can't tell if the bronze straps are weak and need replacement, or if I just need to snug up these fasteners.
You may find that the rotten gunwale is to blame.  The gunwale imparts a great deal of stiffness to the hull.  The thwart design in the Dhow, like drop seats in a canoe, doesn't add much rigidity because the thwarts are below the gunwale and are just hung rather than attached to the topsides.

Another issue is that I'd like to attach bridle lifting points for launch and recovery from the foredeck and I'd like ideas on what/how/where to attach them so I don't ruin the aesthetic of the boat.
I would use really stout inboard brackets for the oarlocks and loop a line through them for lifting.  If you must use top-mounted brackets (because you're a rowing geek and care deeply about getting the oarlocks up and out by an inch and a half), reinforce them and make the hole go all the way through the gunwales so you can run a line.

For the gunwale rail, I've been presented with 2 schools of thought: 

1. Laminate thin battens and epoxy them to the boat until I achieve a rail of the desired thickness

2. Steam the necessary lengths of wood and rapidly clamp them to the hull and rivet them with copper rivets in the original Dyer method.
Find a local source for suitable air-dried or undried wood before getting to committed to steaming them.  Kiln dried wood does not steam well.  Long, clear pieces of air-dried wood of a boatbuilding-oriented species are startlingly expensive to purchase and cost even more to ship than they do to buy.  I reached the point of looking at trees on the stump and writing down phone numbers for custom sawmills before I decided I was on a fool's errand.  Wood can be scarfed for shipping and epoxied back together, but if you're going to do that, why not cut some battens from cheap pine and laminate them?

 
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Ajax

Super Anarchist
14,507
2,801
Edgewater, MD
@2airishuman Looking at the photos above, I agree. The rail must be what imparts most of the stiffness.

I have a place nearby called Exotic Lumber. They'll tell me if their wood is air dried, kiln dried or undried.  Thanks for that tip. I won't need to ship anything.

Regarding the lifting bridle, there is a stout eye on the bow for the forestay of the sailing rig. You're saying I shouldn't put some sort of lifting eyes in the wood on the stern?

 

Elegua

Generalissimo
4,351
1,909
Lower Loslobia
@2airishuman Looking at the photos above, I agree. The rail must be what imparts most of the stiffness.

I have a place nearby called Exotic Lumber. They'll tell me if their wood is air dried, kiln dried or undried.  Thanks for that tip. I won't need to ship anything.

Regarding the lifting bridle, there is a stout eye on the bow for the forestay of the sailing rig. You're saying I shouldn't put some sort of lifting eyes in the wood on the stern?
We hoist ours by the traveler and the shroud attachment points or just craned it up by the bow. 

 

2airishuman

Anarchist
Regarding the lifting bridle, there is a stout eye on the bow for the forestay of the sailing rig. You're saying I shouldn't put some sort of lifting eyes in the wood on the stern?
Using the bow and stern will work but will put more stress on the boat and give you a hoist point that is higher and therefore less convenient.  It's also harder to reach the bow eye if you are attaching or removing the bridle while in the dinghy.

The stress thing, imagine if the boat were full of water or cargo and you were hoisting it, if hoisted from the ends there would be a tendency for it to fold up in the center with the gunwales/topsides pushing out.  Maybe you are going to be nice to your boat.  I am not nice to my tender.

The "chainplates" for the shrouds would be a good choice in front. 

 

andykane

Member
433
199
Victoria, BC
White oak is a good choice for steam bending, although that's a pretty serious curve around the bow so if there's much grain runout then you might run into problems.

Rule of thumb is 15 minutes in the steambox for every 1/4" of thickness.

When building the steam box, try and insulate it a bit to keep the heat in. It's actually the heat that lets you bend - the steam is only a convenient way to transport that heat.  I would angle the box up from the kettle, and leave an opening at the far end so you get good flow of hot steam along the length.

You want to get some bend into the wood ASAP after pulling it out of the box. Put a good bend in that bow portion with your hands as you carry it over to the boat, then fine tune it in place. Getting the major bend in immediately before it cools makes a big difference.

 

Alex W

Super Anarchist
3,306
296
Seattle, WA
Search for posts from wizbang13 on forums.woodenboat.com about Dyer Dhows.  I bought my DD Midget from him and he re-built the whole boat including the coamings.  They were done with alaskan yellow cedar.

I later had to redo the transom of it, the mahogany transom was delaminating from the fiberglass hull.  I sold the boat just after fixing it.

I think Dyer will still sell you the coamings as well, pre-bent.  It would be worth seeing what that costs.

 
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