Active Active   Unanswered Unanswered

open seams in new 5200 Bottom

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

Moderators: Al Benton, Don Ayers, Don Vogt

Post Reply
allanguhl
Posts: 31
Joined: Thu Jul 30, 2015 4:54 pm

open seams in new 5200 Bottom

Post by allanguhl » Wed May 30, 2018 3:48 pm

I am restoring a 1950 CC Riv.and put a new 5200 bottom on it new planks and everything,2 coats of CPES and then 3 coats of 2000e epoxy primer,then I notice cracks in the 5200 seams,the bottom was completed about 3 months ago before the primer was put on, the CPES was put on right after the bottom was completed, any ideas on how to fix this problem ?

User avatar
Don Danenberg
Posts: 175
Joined: Fri Nov 18, 2005 9:30 pm
Location: Manistee, MI
Contact:

Re: open seams in new 5200 Bottom

Post by Don Danenberg » Sat Jun 02, 2018 11:04 am

My guess is that change in your shop's humidity levels allowed the planks to shrink?
CPES is a semi-permeable membrane, not a moisture barrier coat, it does slow, but not stop, moisture movement. It's main job is to penetrate and fill 'abnormal porosity' like open grain and rot spore tendrils. It's secondary job is to glue together the wood fibers at the surface for better adhesion of following coats.
The Barrier Coat Primer is what stops moisture movement. This should have been applied the first day after the CPES applications.
I can only assume that the 3-month period you cite allowed the planks to dry excessively prior to the application of the barrier coat?
In Michigan this year it snowed right up until May, so the last 3-months had not only very low winter humidity levels, but the furnaces were still putting out heat, reducing the ambient moisture levels even more?

At this point, I'd say tape off any open seams and force warmed-up 5200 into them by troweling sideways with a putty knife to force it in. Follow that with tape removal and fairing and a couple more coats of Barrier Coat Primer (I usually do 5 to 6 coats to achieve the 10-mill thickness the instructions call for).

allanguhl
Posts: 31
Joined: Thu Jul 30, 2015 4:54 pm

Re: open seams in new 5200 Bottom

Post by allanguhl » Sat Jun 02, 2018 6:13 pm

My shop is the driveway and I am on the West coast so I am subject to the weather,would cleaning out the seams and using Sika 291 ?

User avatar
Matt Smith
Posts: 847
Joined: Wed Oct 26, 2005 4:14 pm
Location: Reedville VA,
Contact:

Re: open seams in new 5200 Bottom

Post by Matt Smith » Mon Jun 04, 2018 6:22 pm

If you are on the West Coast its very dry there. If the boat is from the other parts of the country shrinkage can happen. The boats on Lake Tahoe can open up alot in that dry climate. Also if you have the boat on a cement slab it can do the same. Maybe, get moisture on the boat and see if that helps. The 5200 moves a bit but not that much. Don is right, He is always right. Winter is also a dry time. I finished a bot with 5200 over a winter, took it to fla and it sat in the sun and opened up a tad.
1948 25' Chris Craft Sportsman
1958 Chris-Craft 17' Cavalier
1937 16' Special Racer
1968 40' Rice Trawler
1968 11' Crab Skiff
2018 Hole in my head

http://www.WoodyBoater.com

jfrprops
Posts: 2014
Joined: Thu Dec 29, 2005 10:41 pm
Location: Powhatan Courthouse Virginia

Re: open seams in new 5200 Bottom

Post by jfrprops » Mon Jun 04, 2018 7:10 pm

why not launch if for a season and see if she tightens up that miniscule bit? I understand your concern if you are at the end of a long restoration and don't want to do anything less that perfect pre launch...but I would Go Boating! But hey, that is my answer for everything!
John in Va
1980 Fairchild Scout 30
19?? custom Argentine Runabout 16'
1954 Whirlwind deluxe dual ckpt 16'
1921 Old Town Charles River 17' (founding Captain, James River Batteau Festival)

User avatar
Matt Smith
Posts: 847
Joined: Wed Oct 26, 2005 4:14 pm
Location: Reedville VA,
Contact:

Re: open seams in new 5200 Bottom

Post by Matt Smith » Mon Jun 04, 2018 7:42 pm

Yup, agree. it should swell up. That west coast dryness is torture on these boats. Talk with the guys at Sierra Boat Co, they deal with this all the time and why so many boats out west are fiberglassed.
1948 25' Chris Craft Sportsman
1958 Chris-Craft 17' Cavalier
1937 16' Special Racer
1968 40' Rice Trawler
1968 11' Crab Skiff
2018 Hole in my head

http://www.WoodyBoater.com

Post Reply