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Plywood underlay for hull sides

Framing, planking and fairing. Repair, or reconstruction. If it's hull related, you'll find it here.

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JimF
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Plywood underlay for hull sides

Post by JimF » Wed Sep 28, 2016 3:56 pm

I know this has been done but I have never done it. I am beginning restoration of an 18' 1935 utility. The side planks are good but a little thin. Here is the method I am considering. Remove all the side planks (hull is braced internally) and clean up the edges. Fill old screw holes in frames.Cut 1/8" marine ply to fit, coat with CPES and staple to frames and battens. There would be a bead of 5200 between the ply and the framework. Coat the backs of the planks with CPES and then a thin layer of 5200 (or thickened epoxy?) and fasten with silicon bronze screws to the frames. Kind of a 5200 bottom but on the sides. Anyone see any problems with this theory?
1930 Chris-Craft Model 100 20' "MOXIE"
1940 Chris-Craft Red and White 25' "Old Paint"
1946 Chris-Craft Sportsman 25' "CinCity"

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Doug P
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Re: Plywood underlay for hull sides

Post by Doug P » Wed Sep 28, 2016 4:45 pm

If you do use this method, keep a photo trail to illustrate what you have done.
Maybe try a diagonal layer similar to the bottoms

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Re: Plywood underlay for hull sides

Post by joanroy » Wed Sep 28, 2016 5:45 pm

Hmmmmmmm, Interesting. I can't think of a reason why that technique wouldn't work. I'd use the 5200 instead of the thickened epoxy to maintain a little flex. Sounds like a fun little project and a great way to get a little more life out of those original old growth mahogany planks. Keep us informed.

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Re: Plywood underlay for hull sides

Post by mbigpops » Wed Sep 28, 2016 7:04 pm

I have seen this done before on a runabout but under new planks.

If you send me a PM I will reply with a link to the photo gallery (not mine but public).

You might pick up some tips.

I am neither promoting nor condoning this method. Your call.

Mark
1953 CC Rocket Runabout "Rocket Man"

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Re: Plywood underlay for hull sides

Post by Tightline5 » Thu Sep 29, 2016 6:49 am

Russ Arrand uses this technique with very nice results. This is now being done more and more on transoms to always have a seem free look because you never get plank edge separation. Russ even has some neat clamps to make life easier. Email him and he will send you some photos.
Phil Jones

1948 US Plywood Executive Runabout Hull #1 "WeldWood"
1954 Racing Runabout R-496
1957 Deluxe Runabout D-17-2062
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Re: Plywood underlay for hull sides

Post by Tightline5 » Thu Sep 29, 2016 6:51 am

Also go to Don Dannenbergs site and search this topic Russ has posted photos there.
Phil Jones

1948 US Plywood Executive Runabout Hull #1 "WeldWood"
1954 Racing Runabout R-496
1957 Deluxe Runabout D-17-2062
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Re: Plywood underlay for hull sides

Post by Greg Wallace » Fri Sep 30, 2016 7:37 am

We call it "skinning". I know of many boats skinned and planked in both new and preservation construction with great success. Epoxy was used as the bonding agent in all that I have encountered. Above waterline only, however.
Greg Wallace 23 Custom 22166 former Chris-Craft dealer Russells Point, Oh.

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Jim Godlewski
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Re: Plywood underlay for hull sides

Post by Jim Godlewski » Sat Oct 01, 2016 5:23 am

I'm wondering if you grow the thickness on the sides how will the stem and transom planks fit? Or would you replace those areas as well?
1956 17 Sportsman CC-17-2310
1930 Model 100 7152

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Re: Plywood underlay for hull sides

Post by Greg Wallace » Sat Oct 01, 2016 6:17 am

The goal is that combined thickness of the laminates equal original. If you are employing this method in a "preservation" effort then original planks would be reduced by the thickness of the under laminate.
Greg Wallace 23 Custom 22166 former Chris-Craft dealer Russells Point, Oh.

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Re: Plywood underlay for hull sides

Post by JimF » Sat Oct 01, 2016 8:39 am

What got me thinking of doing this was that the original planking is only about 3/8" thick from being sanded over the years and that seemed thin to re-use by itself. Combined with 1/8" ply I will get original thickness of 1/2" as well as a much more stable hull side.
1930 Chris-Craft Model 100 20' "MOXIE"
1940 Chris-Craft Red and White 25' "Old Paint"
1946 Chris-Craft Sportsman 25' "CinCity"

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Jim Godlewski
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Re: Plywood underlay for hull sides

Post by Jim Godlewski » Sat Oct 01, 2016 9:20 am

Is the original thickness 1\2 inch? We restored our Sportsman with 3/8 planks throughout. That included a new stem and transom so no issues there for us. No inner side ply either.
1956 17 Sportsman CC-17-2310
1930 Model 100 7152

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Re: Plywood underlay for hull sides

Post by JimF » Sat Oct 01, 2016 10:44 am

To be honest I have no idea how thick the original planks were. However the stem and chines have been replaced and it appears that 1/2" is required. The main reason for using the ply is that I am using the original 80 year old planks and I am sure they are not as strong as they once were.
Thank you all for your interest and support.
1930 Chris-Craft Model 100 20' "MOXIE"
1940 Chris-Craft Red and White 25' "Old Paint"
1946 Chris-Craft Sportsman 25' "CinCity"

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drrot
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Re: Plywood underlay for hull sides

Post by drrot » Sat Oct 01, 2016 10:52 am

Jim,
Looks like they were 3/8".
Attachments
1935 utility.jpg
Jim Staib
www.finewoodboats.com


1947 Penn Yan 12' Cartopper WXH474611
1950 Chris-Craft 22' Sportsman U-22-1532
1957 Chris-Craft 26' Sea Skiff SK-26-515
1968 Century 17' Resorter FG-68-174

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steve bunda
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Re: Plywood underlay for hull sides

Post by steve bunda » Sun Oct 02, 2016 7:49 am

I have repaired a original plank by removing, planning out the pier ding, and reinstalling over thin plywood.
I have also had a boat in the shop that was entirely done with this method, and was failing due to the humidity and temperature swings in the Midwest.
I feel replanking with new mahogany is more desirable for strength, reliability, finishing, and is factory correct.
But , ultimately it is your boat and decision.

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Jim Godlewski
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Re: Plywood underlay for hull sides

Post by Jim Godlewski » Sun Oct 02, 2016 8:19 am

drrot wrote:Jim,
Looks like they were 3/8".
Good stuff Jim, Thanks.
1956 17 Sportsman CC-17-2310
1930 Model 100 7152

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Re: Plywood underlay for hull sides

Post by Russ Arrand » Fri Oct 07, 2016 6:31 pm

I have done this many times on 6 big utilities. Mine included. You need to strip it at 8 inches in the bow. Then about 10 inches to the windshield. After that sheet it. 45 degrees to the chine for the strips. I have some special clamps to clamp the outer planks to the boat that will allow the routing process. I will lend them out if needed. I have seen no movement in the planks I have done with this method.
Russ Arrand
Cadillac Boat Shop

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Re: Plywood underlay for hull sides

Post by DennyDowning » Thu Dec 22, 2016 6:35 pm

You say the side planks are good. You want to make them better. Hmmm.... I guess I would just leave them alone. Also consider if you use 5200 or epoxy the sides will be so much more difficult to repair. I think a 3/8th inch thickness should be sufficient. I would try and save what is there. Use traditional woodworking and boat building materials like wood, paint, bedding and do that right you will have a nice job that will last for years and can still be repaired again later.

Denny

Denny

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JimF
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Re: Plywood underlay for hull sides

Post by JimF » Fri Dec 23, 2016 10:14 am

Just to follow up, I decided to use the old planks in the normal fashion-no plywood. I did replace a few planks that were badly damaged. The problem with 3/8" planks is that they are too shallow to use bungs over the screw heads so all holes are filled with Famowood as was done for this model from the factory. Much progress has occurred since my first post and I will include some pictures. I did use plywood under new decking to minimize seam movement. This boat has no deck seams so even a slight movement would be noticeable. At this point there is stain and a few coats of varnish on the hull and deck and on the cabin sides and top.
I did not want to have to stain and varnish the inside of the cabin while on the boat so I made it in four removeable pieces-the sides, the front and the top. After they are finished they will all be assembled on the boat. I also made the entire cabin 4" taller as there is not much room in there.
Attachments
IMG_1334.JPG
IMG_1332.JPG
IMG_1320.JPG
IMG_1311.JPG
IMG_1285.JPG
1930 Chris-Craft Model 100 20' "MOXIE"
1940 Chris-Craft Red and White 25' "Old Paint"
1946 Chris-Craft Sportsman 25' "CinCity"

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JimF
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Re: Plywood underlay for hull sides

Post by JimF » Fri Dec 23, 2016 10:28 am

For those of you who have never seen a top like this (myself included until this came along), here is a factory photo.
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Factory 1935 Utility.JPG
1930 Chris-Craft Model 100 20' "MOXIE"
1940 Chris-Craft Red and White 25' "Old Paint"
1946 Chris-Craft Sportsman 25' "CinCity"

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Re: Plywood underlay for hull sides

Post by Greg Wallace » Fri Dec 23, 2016 10:56 am

Extremely cool!! I've only seen one. Used to be a regular at the Hessel Show. Have not seen for awhile though.
Greg Wallace 23 Custom 22166 former Chris-Craft dealer Russells Point, Oh.

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Re: Plywood underlay for hull sides

Post by joanroy » Fri Dec 23, 2016 4:59 pm

After seeing the pictures, I searched the essential guide and found you project boat. I think? 26' Sedan: 1922-1930. Where the heck did you find that rare gem? Can you tell us more about her history? Nice work so far. Looks Great!

__opps! Just checked your first post and obviously I'm wrong. 1935, but that top sure looks like the Sedan.

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Re: Plywood underlay for hull sides

Post by JimF » Fri Dec 23, 2016 6:23 pm

s-l1600.jpg
It is a 1935 Deluxe Utility 18' I found it on ebay last summer. The owner had begun the project but had to give it up. He did a fabulous job of putting on a 5200 bottom, had the "B" engine rebuilt and had sourced many reproduction parts like the steering wheel, the instrument panel with three guages including the barrel tach and the cutwater. It also came with the original flat metal framed windshield that was standard if you did not get the cabin top. He told me that the cabin top was a $90 option. Given the factory photo there is no question that this was available. I have good photos of another boat with the top which is probably the one referenced by Greg.

Most of this model boat came with a full bench seat and center steering but looking at the back of the dash I can see that the steering column support was on the right and the pipe from steering box to rudder fits this configuration. Because the cabin is so small I plan on making a few "improvements" to help with usability. At this time my plan is to install a single "bucket" seat behind the wheel similar to what I have in my 1942 Deluxe Utility or most Sportsmen. I then am thinking of a bench seat along the port side with some sort of flip up to make a back for the passenger on trips or flat for easier access. Behind the driver seat might be a fold up/down table with space for a cooler underneath.

I know some of you are going to jump on the originality thing here but I think that this could be a pretty cool "picnic" boat that could be restored back to original, whatever that was, just by changing the interior.
Attachments
cabin top varnish.JPG
varnish.JPG
1930 Chris-Craft Model 100 20' "MOXIE"
1940 Chris-Craft Red and White 25' "Old Paint"
1946 Chris-Craft Sportsman 25' "CinCity"

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Re: Plywood underlay for hull sides

Post by joanroy » Sat Dec 24, 2016 7:21 am

Thanks for the info Jim. I love the boat with that neat little optional hard top. Pretty rare I'm sure. That's huge having the bottom done and the engine restored. Definitely makes the project a little easier to manage.

As far as keeping originality goes, I really think the best way to save an old wooden boat is to make it useable and enjoyable for yourself, or as John in VA says, just go boating! Just saving her is enough and the next caretaker will still be able to go the purist route if he so chooses. Please continue to post photos as you go along. Hope to see her at a show someday. Thanks for the SAVE!

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