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 Post subject: New Plywood Sidewheeler Building
PostPosted: Sun Aug 01, 2010 6:08 am 
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Full Steam Ahead
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Joined: Fri Nov 20, 2009 5:34 am
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Location: Phila PA USA
Boat Name: Margaret S.
Building a flat bottom steam sidewheeler, the project has gotten underway in earnest this month, the hull is very similar to a conventional "Sharpie". Six sheets of Hydrotek Meranti marine plywood, complying to British Standard BS1088, 12mm sides, 15mm bottom have been recieved, and glued up into 20 foot lengths using butt blocks with West system epoxy.

Framing is heavy, and fairly conventional, using Douglas Fir lumber, spaced 16 inches on centers. The frames are built up with polyurethane glue and coated screws. The plan is to glue the sides and bottom to the frames with thickened epoxy, and to cover the hull exterior with 9 oz bi-axial fiberglass cloth set with epoxy.

A few open items with respect to this construction:

Should boat nails or screws be used to attach the plywood to the frames? Or should I just use temporary screws, and let the epoxy do all the holding?

Should I paint the interior of the hull with epoxy, followed by a UV resistant polyurethane, or should I just polyurethane the interior without epoxy? I want to keep the natural wood visible on the interior, in order to be able to detect possible water intrusion.

The exterior of the hull will be painted a conventional color above the waterline, and some have recommended that the bottom receive a coating of epoxy with powdered graphite to better endure groundings and abrasion. Do any of the group have experience with this?

Thanks in advance for information.


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 Post subject: Re: New Plywood Sidewheeler Building
PostPosted: Mon Aug 02, 2010 7:13 am 
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Steam on Deck
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Joined: Sun Nov 22, 2009 8:32 am
Posts: 48
Location: Netherlands / Europe
Boat Name: Panatela
Hi Fred,

Nice boat you gonne build. Looks perfect.
Keep us informed.
Wen we were building Panatela us was told to remove all the screws uit of the hull as soon the epoxy was hard.
The have no use anymore and maybe the go to rust in the wood.
believe me the epoxy is strong enough.

About painting: there are special paintings for epoxy. Aspecialy under water you have to use them.
And doint use DD lack under water, its not waterresistent for a longer time.

http://members.chello.nl/p.schuurs/index%20engels.htm

Piet


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 Post subject: Re: New Plywood Sidewheeler Building
PostPosted: Mon Aug 02, 2010 2:49 pm 
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Full Steam Ahead
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Joined: Fri Nov 27, 2009 5:56 pm
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Location: Northwest Detroit
Boat Name: Iron Chief
fredrosse wrote:
Building a flat bottom steam sidewheeler, the project has gotten underway in earnest this month, the hull is very similar to a conventional "Sharpie". Six sheets of Hydrotek Meranti marine plywood, complying to British Standard BS1088, 12mm sides, 15mm bottom have been recieved, and glued up into 20 foot lengths using butt blocks with West system epoxy.

Framing is heavy, and fairly conventional, using Douglas Fir lumber, spaced 16 inches on centers. The frames are built up with polyurethane glue and coated screws. The plan is to glue the sides and bottom to the frames with thickened epoxy, and to cover the hull exterior with 9 oz bi-axial fiberglass cloth set with epoxy.

A few open items with respect to this construction:

Should boat nails or screws be used to attach the plywood to the frames? Or should I just use temporary screws, and let the epoxy do all the holding?

Should I paint the interior of the hull with epoxy, followed by a UV resistant polyurethane, or should I just polyurethane the interior without epoxy? I want to keep the natural wood visible on the interior, in order to be able to detect possible water intrusion.

The exterior of the hull will be painted a conventional color above the waterline, and some have recommended that the bottom receive a coating of epoxy with powdered graphite to better endure groundings and abrasion. Do any of the group have experience with this?

Thanks in advance for information.


Hi Fred,

Attaching the plywood skin

I would screw the plywood to the frames, countersink the screws and finish them off with bungs. It sounds involved, but it's actually quite easy. They sell combination drill bits for the size and length of screw that also cuts the recess for the bung. Just drill a hole, install bronze or galvanized screw, touch a pre-made bung in some epoxy, tap it in the hole. If you're going to varnish, line up the grain. After it's cured, knock the excess off with a chisel, and sand flush with a block. Your skin material is thick enough for this method. .472" and .590"..

Check Jamestown Distributors for the screws, cheapest place I've found. You could use hot dipped galvanized as well.

On the finishing bright interior:

Have a look at the West system line. They sell an epoxy varnish with UV protection. That's what I used on my Chris Craft. Then I went over the West varnish with several coats of Epifanes spar varnish. The latter just for added UV protection and deeper effect. There is no substitute for good quality finish. I've owned my Chris Craft for almost 20 years, and have learned that from experience. It's current finish is around 9 years old and still looks good, just a recoat of Epifanes in the spring to restore the UV protection. For paint, I've always used the "Pettit Topside" line. Jamestown Distributors carries everything I've mentioned here.

Bottom coating:

I would definitely put a layer of epoxy cloth on the bottom to the waterline, and build it up in high abrasion areas. The old Chris has a glassed bottom, from 1964, it is still in great shape.

There is about a million combinations to do what you're asking, I'm just mentioning what's worked for me.

-Ron


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 Post subject: Re: New Plywood Sidewheeler Building
PostPosted: Tue Aug 03, 2010 1:04 am 
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Full Steam Ahead
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Joined: Fri Nov 20, 2009 10:12 am
Posts: 193
Hi Fred,

Nice looking boat!....hard chines are great for stability and ease of build.

Some lessons learned from building Rushforth that I thought I would share with you as she is also hard chined.

Coat all of your ply BEFORE you cut and fit it. It simplifies the job more than I can describe. 2 coats minimum.

As far as interior, I would glass it too, at least below the chine in the bilge.
My reason?
You will be soaking it in water, oil and ash and then drop every sharp metallic object you ever bring on board on it, sharp side down! If it's glassed, it has some armor. You can still see through 4 oz glass, proof being my deck which is glassed over and then epoxy coated and varnished.

On the outside, I would put cloth down from the keel down over the chine by 2", and then again from 2" above the chine to the sheer. This doubles the coverage over the chine which will take a real beating on rocks and trailer bunks. Finish the chine before glass with about a 1/4" to 1/2" radius and the glass will go down alot easier.

BS1088 is the way to go with the ply. I cut all the stamps out the panels and kept them for when I insure the girl.

On the inside, looking at your design, I would be inclined to glass the inside surfaces after you splice/scarf the panels together but before you cut the panels to size and install. All the work will be in the flat and it's much easier to get cloth to lay down that way.....A lesson learned the hard way :roll: ....If your really torturing some panels to bend around the stem, you may want to experiment with how much the glass will stiffen the panel.

As far as frames are concerned, I think you can get away with just coating them with two coats of epoxy and UV varnish after assembly.

A good poly varnish I think is the way to go if your naturally finishing things.. I have a traditional high UV protection varnish on my boat but the varnish is already showing its age.....It will need some work this year.

I am a fan of bronze screws and nails if possible. If you ever have to perform surgery, your tools will thank you....and they don't ever rust....But I will admit to some deck screws in the frames and keel. They are very convienent. Jamestown is a great place.

I have a line on some bronze hardware at other places if your interested.

I would glass the bottom before the keelson goes on. Some people call this the worm shoe. I put the keelson on over the 10 oz bottom cloth and glassed over the keelson with 10 oz tape. I have zero fear of rocks with this as even if I tear the keelson all up, it can be replaced and the cloth underneath will stay intact. It is bonded with thickened epoxy and bronze lag bolts. It's not going anywhere anytime soon.

11% of the rudder area ahead of the rudder post for balance....works really well.

If this is your first design, I would suggest Weston Farmer's book " From my old boat shop" He talks about 1/16" scale test models to prove your stability and floatation calculations.....IT WORKS:D

West System all the way.....I trust the stuff, and I've shlepped enough of it.....Id say over 40 gallons of it...to say I trust it.

A shed to build her in. I built a "bowed roof shed" and I can highly recommend it to other builders. They are very strong and cheap to build.

I used "graded base" for the floor in my boat shed. I built on bare ground. It's a form of crushed stone. It compacts nicely and is very stable.

I know this is rambling,,,,so I'll stop now......but if you need some help, just yell

Good luck to you!

Dave


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 Post subject: Re: New Plywood Sidewheeler Building
PostPosted: Wed Aug 04, 2010 2:20 am 
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Have about 2/3 of the frames set now, 3 gallons of Epoxy and 20 yards of 50 inch bi-axial 9 oz cloth is on the way.


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 Post subject: Re: New Plywood Sidewheeler Building
PostPosted: Wed Aug 04, 2010 2:33 am 
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Frames are 1.5 x 3.0 inch Douglas Fir, screwed and glued, with 15 MM plywood corner braces


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 Post subject: Re: New Plywood Sidewheeler Building
PostPosted: Wed Aug 04, 2010 2:37 am 
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Corner bracing, with glue, which is plentiful to assure no voids. Galvanized staples hold the braces to the frames. After the glue begins to set (about 2 hours), excess is scraped off with a sharp chisel.


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 Post subject: Re: New Plywood Sidewheeler Building
PostPosted: Wed Aug 04, 2010 2:48 am 
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piet, thanks for the encouragement and reply.

One thing I did not understand in your reply, "And doint use DD lack under water, its not waterresistent for a longer time"
Could you please explain?


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 Post subject: Re: New Plywood Sidewheeler Building
PostPosted: Wed Aug 04, 2010 9:02 pm 
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Warming the Engine
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fredrosse wrote:
piet, thanks for the encouragement and reply.

One thing I did not understand in your reply, "And doint use DD lack under water, its not waterresistent for a longer time"
Could you please explain?


Heh, looks like piet's been drunk posting again! :lol:

(Just kidding piet!) ;)


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 Post subject: Re: New Plywood Sidewheeler Building
PostPosted: Thu Aug 05, 2010 12:36 am 
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Thanks for advice DetroiTug.

DetroiTug wrote: I would definitely put a layer of epoxy cloth on the bottom to the waterline, and build it up in high abrasion areas

The plan is to use 9oz cloth on the sides and bottom, 9oz double thick on the chines and keelson. Then another layer of epoxy saturated with the graphite powder.

What I am looking for is any experience with the graphite powder?


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