attaching the deck to the hull

[bluemarble]

On a 40’ mahogany strip-planked hull what are the easiest / most effective methods of attaching the deck? I have read a few books on wooden boat construction, and I have not seen one that describes the method that I was told by a friend who is a naval architect.

What my friend said was to attach stanchions to the inside of the hull that extend up to the level of the rail and spaced about a half meter apart. Then I should attach what I think is called the deck clamp or shelf to the stanchions at the deck line. When I lay my deck beams now they will be supported 2 inches away from the hull because they are sitting on the deck clamp that is attached to the stanchions.

Every book that I have seen shows the deck clamp attached to the hull and the deck beams attached to this clamp / shelf. But every example I have seen does not have permanent rails like I will have. Does anybody have any suggestions?

Should my deck clamp sit off from the hull or should I attach the clamp as separate pieces in between the stanchions? This seems like I would loose some structural support if my deck clamp is split up though.

I’ve attached a drawing of what I was told to do, but I am not the best artist, so hopefully it will help. The ship is a Bruce Roberts Spray 40.

Thanks,
Matt

[gonzo]

The problem with stanchions is that they are a source of leaks.

[bluemarble]

Hello gonzo,
would there be a better method to attaching the deck and still keep the original look of the ship?

[gonzo]

Will the hull and deck be fiberglassed over or just painted?

[bluemarble]

Nope. The hull will be epoxy coated and painted, but no fiberglass. The deck will probably be varnished only.

[Hunter25]

Any penetrations through the deck will be a source of leaks given time and lack of care.. Some designs have them sistered against the frames, others are the frames, some land on deck with a backing plate underneath. The clamp should stand away from the hull and capture the frames heads and or stanchions, clamping them in place. The deck beams usually will be notched into this. The clamps you may have seen in books or other boats may not have been a clamp, but a sheer shelf, which usually does lie against the hull. There are many different approaches used, some better then others, none perfect.

Do not varnish the deck, you will not be able to walk on it when it is wet.

[bluemarble]

Thanks for the info Hunter25,
If I attach the deck beams to the clamp should they also be attached to the hull? The beams will extend beyond the clamp, correct? Do you know of any resources (books / websites) with information about building a boat this way?
Here is a link to a bunch of pictures of my boat.
http://matt-barker.com/boat/boat_moving/

Thanks again for your help, I really appreciate it.
- Matt

PS - the deck will be teak and I will probably oil it. Didn't mean to write varnish.:)

[yipster]

seeing the pics i almost start liking wooden boats again :cool:
stancions on bulwark on a wooden boat?

[Hunter25]

You should use the setup Roberts designed into that version of his Spray series for your beams. You could cause a world of hurt for yourself if you start changing the way structural pieces are attached or held together. If you do not have plans, get them. It is a small price to pay for having things go together right. Roberts also has a support group that may be some help, but I do not know the web address.

[gonzo]

Is your naval arquitect friend modifying a Bruce Robert's design, or are you showing a Bruce Roberts only as an example of the type of boat?

[djwkd]

surely there must be a type of 'marine glue' or something,that would be your best option, but im a newbie so...if i were you id get someone elses approval.

[djwkd]

looks like a nice boat,how bug is she?

[djwkd]

how big is she,sorry.

[bluemarble]

Is your naval arquitect friend modifying a Bruce Robert's design, or are you showing a Bruce Roberts only as an example of the type of boat?
Gonzo,
The design is a 40' Bruce Roberts - Spray
The original owner was going to modify the design of the deck (add a pilot house) but I am going to stay as true to the original design as I can. I may change small things, but nothing that will affect the boats performance. The picture I posted earlier is close to what my ship will look like. I have the plans for the gaff rigged schooner.

Do you know of the best way to avoid leaks at my stanchions? or any advice about some methods for building this style boat?

Thanks,
Matt

[Deeman]

Do you know of the best way to avoid leaks at my stanchions?
Drill Oversize holes.
Fill with epoxy
Drill holes for bolt size.
Mount backup plates with 5200
Coat bolts with epoxy or 5200 and install.
Use bolts & nuts - no screws.
Takes forever- last forever- strong, no leaks.

I'm making alum back-up plates now.
Eric H

[djwkd]

Gonzo,
The design is a 40' Bruce Roberts - Spray
The original owner was going to modify the design of the deck (add a pilot house) but I am going to stay as true to the original design as I can. I may change small things, but nothing that will affect the boats performance. The picture I posted earlier is close to what my ship will look like. I have the plans for the gaff rigged schooner.

Do you know of the best way to avoid leaks at my stanchions? or any advice about some methods for building this style boat?

Thanks,
Matt

itll be impossible to change something without affecting the performance,maybe without NOTICABLEY affecting the boats performance

anyway,could anyone tell me how THEY attach the deck vto the hull?just screws or is something more needed,bolts, marine glue.......?

[Hunter25]

Do not use 3M 5200 as a bedding compound, it lacks flexibility and has a tenacious grip, which will ruin most things they are bonded with. Use 3M 101 or something like it for bedding, which has a much higher flexibility and moderate grip. Bedding has to be redone every so often, the part has to be removable, 3M 5200 will make this almost imposable.

Drilling and filling the mounting holes for stanchions is a very good idea and recommended. So is the use of through bolts. If it needs to be strong use through bolts and big backing plates. Your stanchions go through the deck and sister the frame heads. This means the backing plates and bonded bolt holes are not necessary for your boat, but is good advise for other attachments. The only true way of minimizing leaks at these penetrations through the deck is with a good caulk and constant eye toward maintenance of these seals. The deck and stanchions will move around during use and the caulk will need to be flexible enough to remain attached. Keep and eye on them and redo the caulk when it looks like it may be letting go or leaks develop.

[ChrisF]

<i> I am going to stay as true to the original design as I can. </i>

So, as Hunter25 suggests but was too polite to ask, how *does* Robert the Bruce show to attach those high bulwarks?

In a steel boat it would be a piece of cake. In a wood boat I'm dubious about putting those bulwarks on at all, because they WILL be difficult to attach securely and they will potentially be subject to some enormous loads...falling off a wave, having a wave fall on you, coming alongside, getting smushed against a tug in the Panama Canal (been there). Lifelines let all the water pass harmlessly through; those bulwarks are going to take a huge hit with every wave. They're also a lot of windage.

If I HAD to have something like that, I think I'd put them on with metal bracket stanchions, secured into the deck and clamp with studs potted in epoxy. They'd be pretty strong and very much in the way. If they did get torn out, they wouldn't take huge chunks of structure with them -- they might even just fold up like lifeline stanchions and let you remove them in a civilized manner.

Running wood stanchions or frame heads through the deck dates back to carvel planking with fasteners, where you just figured on replacing rotted or tired parts every now and then. Those stanchions were a sure source of rot in that form of construction. Nowdays you could seal them up somewhat better with epoxy, but on the other hand, if you DID get some rot in the clamp, with your glued construction, what a nightmare! Rather than unscrewing some screws, you'd be taking the chainsaw to her. And when you got smushed against a tug and busted 'em all off, even if you didn't pry the boat apart in the process, you'd be back to bolting on metal brackets.

Under no circumstances cut your clamp into bits. It's a major part of the system that supports longitudinal rigging loads in a wood boat, and should be large and continuous, balancing the large and continuous keel structure like the top flange of an I-beam balances the bottom flange (the deck being full of holes and unreliable).

Doesn't Roberts show construction details?

[Hunter25]

I have seen the plans for a smaller Roberts Spray and the deck beams are let into the top of the clamp with a sloped notch, which is normal practice. It is also kind of common to see sistered stanchions poking through the deck, but I do not like the idea much. Work boats had this construction and it is very solid as long as you keep up the caulk. Bluemarble originally posted some confusion about shelves and clamps which I think he has transposed in terminology. Shelves are usually fitted between each frame bay at the frame head, though I have seen small boats with a shelf atop the frames, they generally are cut up for each frame pocket. I have found larger boats carry both a shelf and a clamp, where smaller boats can have one or the other or both. Deck beams fall on the clamp or a frame.

The larger Sprays are big boats. The bulwarks on these boats is work boat style and massive. It is not to probable that a stanchion base of steel with a big packing plate will hold up these pieces. The first bump at a dock will tear them loose from the deck. Near the bow these are close to 3' tall and need to be part of the hull, not just bolted to it. I do not think the planking is attached to them, they just sister the frame tops. They also carry the chain plates, so they need to be very strongly mounted. I think this is why the old work boat style of construction is used for these parts. There is nothing better that will carry the huge rigging and rub rail loads that they will have to tolerate.

The guy in the slip next to me has a 1960 motorsailor by Atkins which has the exact same setup on the bulwarks. His boat is 37' and heavily built. The bulwarks were replaced after hurricane Charlie dropped a tin roof on them. It was their first replacement, he thinks and there was some rot. Two deck beams were scabbed and all the sistered stanchions and bulwark lumber was replaced. His boat has had pretty good care, but it is no fancy yacht by any stretch. It is just built like a tank and can take the abuse. The Spray series is from the same train of thought. Pretty typical stuff for a work boat.

[Tad]

Blue,

What does the design show?...nothing? I'm not surprised.

Your friend is right, bulwark stanchions are the traditional method of dealing with this area. But their use guarantees the entrance of fresh water into the joints and eventual rot. The notched and perfectly fitted covering board is particularly difficult to get right as well.

This area is one of the most critical in the boat, why? Because everything you hit, piling, dock, another boat, etc, will hit right at the deck edge. This causes movement of the wood pieces, joints open up, and water gets in. That's bad.

I assume this boat has transverse frames? Cut them off below the sheer and laminate a big clamp/shelf over the frame ends and right up to the sheer line. Notch the ends of the deck beams into this clamp, these should be tapered notches, depth about 1.5" on top of the beam, 0" on bottom. Fasten the beams with glue and a big screw from the top of the beam, angled down and outboard into the clamp. Put lots of screws into the clamp from outside the planking, plug the holes.

Lay your deck over the beams and clamp right out to the outside of the planking. Under layer should be plywood, which has to stop short of the outside edge because you don't want to expose ply edge grain.

Then build metal brackets to support the bulwarks, a flat plate lag bolted to the deck as a base with angle brackets vertically to bolt the wooden bulwark onto. The vertical angles should be deep where they meet the base, perhaps 6", and tapered to the cap (perhaps 4" on top) Leave lots of big gaps in the base plate so water can run off the deck.

Tad

[Hunter25]

This is a larger (45' I think) strip planked Spray, The bulwarks and chain plates are visible and it shows how massive these pieces are.

http://www.bruceroberts.com/public/HTML/images/S45COSTELLO.jpg?SSImageQuality=Full

As leak prone as the sistered stanchions may be, it is one of the few ways that will support the rigging strains. The bulwarks flair out a lot in the forward sections and will be all the fending, by way of a pile or dock, so they need very solid attachment. I do not like sistered stanchions either, but I can not think of a better way to give the support necessary. Metal packing plates and stanchion bases would be fine on low bulwarks, but not on these. The Roberts plans do show the deck beam joint details and are complete. Thousands have been built.

Log on to his site http://www.bruceroberts.com/public/HTML/BRUCE.htm or email him directly by email at design-office@bruceroberts.com or call in the USA call Hal Whitacre NA, 410/279-2525, or 61 (0)7 5450-1962 is the international number (I think)

I hear he is easy to understand and helpful. Talk to the horses mouth and clear up any confusion.

[bluemarble]

wow, I didn't expect this much reading this morning. Thanks everyone for helping me out. I think I will get in touch with Bruce as soon as I can for infrmation regarding the original design. As far as leaks go, I think I am more concerned with solid construction. I am good about maintenence and I think I can prevent most rot and leaks with some good yearly maintenece. I just don't want the ship to break in half when I come alongside the fuel dock.

I have much more to say, I'll write back sometime during the day with answers and more questions. Thanks again everybody.

-Matt