View Full Version : mixing seam compounds for spot repair

05-29-2017, 12:20 PM
my carvel boat has been on the hard for about six months..

i have scraped loose paint and touched up spots with fresh bottom paint,
but there are some spots where seam compound was partly missing or pulled out when going over with the blade

i suspect the original seam compound is 3M 4200 or something similar and seems durable enough,
but i do not like the way it breaks up when scraping or the fact that the bottom paint seemed to adhere poorly here
(particularly, i think, on the thin layers of squeeze out where the previous owner did not mask next to the seams)

i don't see any cotton or any very wide gaps.. from my neophyte's perspective everything looks pretty tight..

At this stage, would it make sense to go over with a more traditional putty type seam compound before the next coat of bottom paint and going back in the water ?
or do i need to be careful and stick to the goo that was originally used ?
or am i overthinking ?
and if there is no cotton exposed i can just finish the painting and call it a day ?


05-29-2017, 12:34 PM
some photos of the areas in question:

https://c1.staticflickr.com/5/4247/34839984091_2f5e56f0f2_z.jpg (https://flic.kr/p/V5G2sT)

https://c1.staticflickr.com/5/4273/34839985001_2207f65db6_z.jpg (https://flic.kr/p/V5G2Jz)

https://c1.staticflickr.com/5/4247/34839985861_d9d2d54876_z.jpg (https://flic.kr/p/V5G2Zp)

wizbang 13
05-29-2017, 12:49 PM
Looks like white cedar planking?
If so , those seams will close right back up, quickly, a few days tops. I would not mess with them , but I would camp out on the vessel for a bit after launch.
A hardwood planked vessel will swell slower, but it will shrink slower and less.

05-29-2017, 12:57 PM
yess you got it
white cedar it is

so i guess the small chunks of missing compound are not worrisome

wizbang 13
05-29-2017, 01:09 PM
Some may put slick seam in there, but that gets messy down the road.
Some may make put sawdust under while in the water, but that can interfere with the fairness of the seam down the road.
Some may make a paste of soapfakes, which dissolves and goes away soon.
I just would leave her be.I believe she would be best left alone.
I do not see missing compound, just small open gaps from normal plank shrinkage.

06-05-2017, 08:26 AM
thanks again for the advice and confidence.. i think it came out great just scraping and sanding..
i think it's a big improvement !

here's some before, during, and after pics:

https://c1.staticflickr.com/5/4261/34948187972_d23676c051.jpg (https://flic.kr/p/VffAH3)

https://c1.staticflickr.com/5/4290/34948190422_2b30ffcc43.jpg (https://flic.kr/p/VffBrh)

https://c1.staticflickr.com/5/4230/34982098931_c3219a22c2.jpg (https://flic.kr/p/VifpfK)

https://c1.staticflickr.com/5/4288/35112910955_ace726c680.jpg (https://flic.kr/p/VuNR7t)
https://c1.staticflickr.com/5/4236/34948419922_7556216f92.jpg (https://flic.kr/p/VfgMEb)

https://c1.staticflickr.com/5/4251/34726437580_02e399e813_z.jpg (https://flic.kr/p/UUE53q)

Jay Greer
06-05-2017, 12:12 PM
With the exception of the drop keel, your hull reminds me of the Sea Bird Yawl that was designed by Charles B. Mower and Thomas Flemming Day Day was the editor of the Rudder Magazine at the beginning of the last century. If it is based on a Sea Bird. You might be happy to know that many great adventures have been experienced in that design. Two of my friends once sailed theirs to Hawaii. Captain Voss capsized one in a typhoon off of Yokahama during a delivery. The Ship Mate coal stove came adrift and planted a imprint of Ship Mate in reverse in the overhead!

As to the seam compound, More than likely it is oil based. Oil based seam comound has the advantage of not reaching a point of complete compression, something that is most desirable when using cedar planking! No matter how much the planking swells, after launching, it will continue to pooch out of the seams there-by preventing cracking of the frames or starting of the plank fastenings. I would recommend using oil based seam compound for paying your seams again! After many years, it will harden and then it is a matter of reefing the seams and putting in new compound.
Interlux still makes an underwater oil based seam compound. I think you would be wise to use it! If indeed it does pooch out, it can be sliced off with a sharp putty knife or chisel when you haul out next time. |:)

06-05-2017, 01:02 PM
thanks she reminds me of a Sea Bird too.. I have here a first edition of Harry Pidgeon's 'Around the World Single-Handed' and the little catboat does look a lot like his 'Islander' to me..

the seam compound is not oil based.. definitely some kind of polysulfide or similar.. very rubbery and resilient, but breaks up and peels in areas where it was spread out thin... that's all that white that you can see on the hull; where the paint did not stick well.

i did end up picking up some of the Interlux brown seam compound just in case, but I followed wizbang's advice and did not end up using it.
the seams certainly started to look a lot better to me once they got filled with a bit of paint,
but the real test of time will be how she looks next time she's out of the water ! (next year ??)


Jay Greer
06-05-2017, 03:27 PM
I met Harry Pidgeon with my dad when he had "Sea Bird" on display in San Pedro back in the 1940's. I was too young to understand what a voyage around the world was but I do remember my dad had a great time chatting with him.

Jim Ledger
06-26-2017, 04:49 PM
Those seams are fine, just put her in the water with a freshly charged battery and keep an eye on her for a day. The less crap jammed into the seams, the better.

It's always best to haul out late and launch early. This time of the year the sun plays hell with a wooden boat on the blocks.

06-27-2017, 05:08 PM
thanks, Jim.. that's basically what i've done

late haul was achieved this year (november)
but the launch may be late as well (hoping for next week)
luckily she was on the dirt and in some partial shade

ideally she would stay in the water year round... seems like the river up here rarely ices up

Jim Ledger
06-27-2017, 05:33 PM
Get her in the water and start sailing her, have an adventure...that's the best thing.

Oh, and change the oil, straight 30 weight.