Sikaflex removal

[Rock Doctor]

David,
I successfully resolved a leak into my ballast tank from the starboard floor seam. The floor was flexing quite significantly and cracking the sika which seemed to have lost its elasticity. It was partially old sikaflex but mostly due to poor adhesion of the epoxy used to seat the floor to the hull.

I removed the Sikaflex mechanically using stanley knife initially then a 25mm paint scraper sharpened on an oilstone. Turps, white spirit, alcohol or petrol were not effective. I cleaned the surfaces as best I could mechanically. I then used a Dremel with an abrasive wheel to remove the hard ?epoxy or whatever the adhesive was below it, after which I used thickened epoxy sludge to refix the floor. Sikaflex then to fill the gap.

I note that now the sika is starting to crack, perhaps shrinking, all around the seals behind the seats as well as the floor so, shudder, I am looking at repeating the procedure. Worryingly there is a significant leak from the ballast tank into the front buoyancy tank. To fix that I may have to remove the floor (top of ballast tank. That is a big job.

To take my mind off that sailing season starts here again next week and with news sails Gryphon should be flying - I hope.

Regards to all.

[Graham W]

Chris,

I hope that you manage to get Gryphon sorted out for the season.

Looking specifically at your problems with the Sikaflex seals I’m wondering if some of it could be down to heat and UV damage?  Perth’s latitude, if transposed to the northern hemisphere, would place you well south of Europe and on the northern edges of the Sahara Desert.

There must be some downside to all that gorgeous weather (he says enviously)!

[Sea Simon]

Hopefully you're on to something there Graham, with the UV?
Is the boat in question covered when not in use i wonder?

I'm appx 185 miles N of Tobruk, N Africa at the moment.....
 That sounds so much more exciting than S Crete!   

I was looking at some local boats only yesterday, and was amazed by the amount of UV (and possibly "grit blast" damage, from the high winds and quarry-like landscapes here in Crete!) damage to what i would think are quite new boats.

Makes my ongoing battle with the gulls in Cornwall seem quite trivial!

[Rock Doctor]

Graham,
I don't think UV is a big problem for me as my boat is under is boat cover and in my carport also sheltered from Ol' Sol. Here at 31.95 deg S and 115.86 deg E heat is probably more of an issue. We get over 40 deg C here in summer but average daytime is more like 30 and I suspect that the solvent that is supposed to keep Sikaflex plastic is being distilled off.

The worst place I lived with a yacht was Pannawonica up in iron ore country 21.64 deg S 116.34 deg E where summer days were all over 40 deg C and never under 20 deg C overnight. In those days I owned a Heron which I previously sailed on salt lakes near Kalgoorlie when there was enough rain to fill them - every 10 years! Anyway Pannawonica took a terrible toll on my Heron with all the timbers shrinking and seams opening up. Those were the days of Resorcinol glues. P.S. I took a Canadian geologist out into the bush on the hottest recorded day when I was there - 49.6 deg C behind the Stevenson screen. Anyway I cooked him eggs and bacon for lunch on a shovel we left in the sun - impressed him no end. My guess is that the valley we were in was over 60 deg C - no wind. Tough days for geologists in the NW of Western Australia.

[Peter Cockerton]

Just spent the morning removing the sealant around the ballast tank primarily because it looked unsightly with black mold marks within the sealant. As previous posts I used a Stanley knife to remove the initial bulk of the sealant with horizontal then vertical cuts which released a slither of sealant. I then used a "plough" shaped scraper I fashioned from a cheap Tesco cutting board to scrape out some of the remainder. White spirit and plenty of elbow grease cleaned the area quite nicely afterwards.

I did speak to the yard on suggested sealant colour replacement, on the early BR20's they apparently used white sealant they now used black I’m told as it lasts longer without discolouring.

Two questions

Some sealant still remains in the bottom of the groove around the ballast tank which will be difficult to get out cleanly, have others left this in place and applied the new sealant on the top of this.

I have applied a small section with white sealant and I’m not sure whether I like it or not, has anyone a later BR20 with black sealant and can comment on whether they think that looks good or not.

Peter C