Discussion in 'Boat and Accessory Building' started by Dan_Millsip, Oct 1, 2007.
Rub rails are installed -- they were a lot more work than I thought they'd be:
You could learn a thing or two from your daughter Dan... a picture of you sitting in the boat, paddle in hand, balancing on the workbench would be greatly appreciated and make a lovely Christmas card to loyal WCP subscribers.
I like that shop with all those nice cabinets and racks on the wall looks like it's well organized!
Lookin' very good Dan. Although they are non-traditional (for kayaks, that is) I like the rub rails - same as on all the Bear Mountain cedar strippers. Did you glue and screw (and then plug the recessed screws)? Looks like you decided not to slot the rails for soft pad-eye loops....
I glued and nailed the rub rails (with the provided brass nails) as per the instructions. There were a lot of work to do and I'm not entirely certain that they are of great benefit on a kayak but they do look pretty nice on the boat.
I've done a bit of fastenng of similar protective strips, and favor bronze screws, just so I can adjust the position, if needed. But, those ring nails will hold forever, and are easier to set and protect.
In a wood boat, with a solidly placed sheer clamp underneath such as Dan has, the rub rails are not at all needed for structural integrity. Their main function is to prevent any water entry into the sheer joint, in the event of a serious rail bruise.
I think they are worth it ... inasmuch as I just rehabbed a failed scarf joint in a similar protective strip on the power boat. Because the protective strip isolated the underlying structure from water intrusion, I did not have to worry about that, and could concentrate on fixing what could be seen.
In a sense, the rub rail is "sacrificial" -- it is a lot easier to replace than a larger area that has rotted along the grain of the plywood after water has penetrated the sheer.
After much more sanding, the boat is ready for LPU:
Just completed a 15 hour finishing marathon -- prepared the shop and applied nine coats of LPU to the boat (4 on the hull, five on the deck):
Close-up of hull:
Deck and hull completed:
Close-up of front of coaming:
Top view of bow:
Top view of stern:
Another view of the completed boat:
A little buffing and polishing and it should look pretty good.
Uff da! Dan, you are an animal! With the time windows the LPU mandates, you must have been a whirlwind. I assume you are doing a coat an hour, and that you did the hull, then the deck, yes?
Also, what are you using for a hydration scheme? Practically everyone I know who uses that LPU claims the higher the humidity, the better ... you?
Yup, it worked out to about a little more than an hour per coat and I did the hull first. It took about 30-35 minutes to get all the way around the boat and then I waited about 30 minutes for the LPU to get dry to the touch before applying the next coat (I left an hour and a half after the last coat on the hull before turning the boat over).
The humidity in the shop was just above 50% for the past couple of days -- I sprayed with a spritzer bottle quite a lot before starting (mostly to clean the air of as much dust as I could), and this increased the humidity by 3 percent. Temperature hovered around 22 degrees celsius (about 71 degrees farenheit). This seemed to work out really well -- I had to work quickly, but not so fast that I felt pressured. However, I did have to have everything right handy in case it was needed -- you can't stop and there's definitely no time to do anything else until the area being worked on is completed.
I learned a couple of boats ago that there's absolutely no going back with LPU -- once you've tipped it off, you CANNOT go back -- not even to fix something that's a couple of feet behind you -- doing so makes a mess as the LPU sets up quick when it's thin. When applying the LPU I find that you can see brush marks but a few moments later, the LPU flows out nicely and the brush marks disappear -- I find if you work the LPU too much, the brush marks remain as the LPU doesn't have a chance to flow out before setting up. So, getting a good finish requires you to realize that you must do your tipping off quickly and let the LPU do it's stuff (flow out) even though it looks like it needs to be worked more.
I added about 15 percent distilled water to the LPU and also added the cross-linker to all but the first coats.
Temperature and humidity gauge in the shop -- it's helpful to know just what the conditions are:
Hunh. I may need one of those humidity meters.
IIRC, you brush the stuff on with a bristle brush and then tip with a foamie, yes? Or, are you rolling and tipping (with a foamie)?
I tried the former on the hull of the power boat when I was laying on a lot of paint, and could not make it work on near-vertical surfaces. Any wisdom on that for the rest of us? [On very small jobs, I just use a foamie, for the brushing and the tipping.]
Also, I find I have to renew the foamie on longer sessions, dipping it in water and squeezing out the congealed LPU so the foamie remains useful for tipping. Any issues with that for you?
Technique seems very critical with this stuff, so I am very interested in what you have found works. I am always learning from youse guys.
I used a foam roller (the yellow ones from West Systems -- cut in half) and then tipped off with a foam brush. I really made an effort to put on thin coats -- in most areas I think I was successful but there were a few spots where it was a bit thick (got a run or two, nothing serious but I was trying really hard not to have any runs). I think applying LPU to vertical surfaces would be difficult since the stuff is so thin to begin with. The only thing I could suggest is to thin the LPU out a lot with distilled water (maybe 25 percent?) and apply as thin as you possibly can (I find occasionally that the roller has way more LPU than I'd like on it -- same with the foam brush).
As far as rollers and brushes go, I used three rollers and two foam brushes for the whole job. Didn't have any congealing issues. When I was loading the roller I only slightly dipped it into the LPU, minimizing the amount on the roller -- perhaps not overloading the roller made a difference? I did find the foam brushes to overload often and I'd squeeze a bit out on the next section I'd be working on just to off-load the brush a bit. Seemed to work OK.
I've learned a fair bit about technique with this stuff and you're right Dave, technique is very important. Everything must be done methodically and without hesitation. I'm still learning lots about this and I'm quite pleased with the overall outcome, although it's not perfect. If I were just looking at protecting the boat and my main objective was to get it in the water, I'd call it done right now and would be quite happy with it. I've seen many boats on the water that have had worse finishes and this one is not bad, but it's not really up to what I think is a really nice. Once it's had a chance to fully cure, I'll buff it (judging from how well the finish has turned out so far, I know that it's going to look really nice after it's buffed and polished.
LPU might seem like a lot of hassle compared to varnish but the stuff lasts for a long, long time -- I think it's worth the extra effort to be virtually maintenance free for about 4-5 years.
Here's my set up for beginning the application:
- Paint tray
- Cross-link drops
- Mixing cup
- 2 1/2 ounce measuring cup for LPU (use it to dip into the tin)
- 2 1/2 ounce measuring cup for water (keeps the mess down)
- 5 foam roller brushes (one on the roller)
- 1 bristle brush (for doing the riser on the coaming)
- 3 two inch foam brushes
- Stir sticks
- Distilled water
I also have paper towels handy to wipe up any drips.
Great job on the LPU topcoats Dan. Your boat looks awesome! 8) Just curious, would you ever go back to spraying on the LPU for your next build as you did with the Coho?
I agree that preparation is key before applying this stuff. Spritzing the air and hosing down the garage floor also works for me in addition to having several backup sets of dry foam brushes/rollers on hand. After each coat, I washed the brushes and rollers, air dried and rotated them for the next application. I can't say for sure but a cooler 65 deg ambient temp in the garage might have worked in my favor when I finished the Silver. Proper lighting to see ones work is equally important particularly after applying the initial coat.
Your advice with respect to the application technique is spot on. Maintaining a wet edge and tipping off in one smooth stroke, starting from dry and finishing into a freshly rolled coat also keeps the number of visible brush strokes down to a bare minimum.
These posts by Dan and Art are very useful, I think, to folks considering using the two-part LPU. Perhaps it might be good to separate these out as a separate topic for greater visibility for others? I am a huge fan of this paint, but most folks I have mentioned it to are scared off by its reputation, especially folks considering spraying. System Three has been remiss in not providing the details needed to easily work with it.
Art and Dan could teach System Three a bit about how to communicate use of their own product!
[BTW, I'd add to Dan's list, a large capacity plastic syringe -- which I use to draw LPU out of the paint bucket and deliver to the small-batch mixing container. Less waste, and less chance of dribbles. The one I use goes to 30 ccs, and the tip has a roughly 5 mm ID opening, which makes transferring LPU for small jobs easy and quick. Immediate rinsing of the syringe after use seems to keep it clear for future uses.]
astoriadave just wrote:
just a precaution - wash out syringes or any other new plastic material with soap and water before using for any finish or resin. Unbelievable as it may seem, i have had major resin fisheyes from a new sealed medical syringe.
I might. It certain uses a lot more material though. I used more than two quarts when I did the Coho -- by contrast, I used just a little bit more than a quart rolling and brushing it. If I had easy access to a spray booth, I would definitely work on spraying -- I think with some practice,LPU could be sprayed without doing any extra work (sanding, buffing). I also wanted to brush the LPU on again because I did have pretty good results when I did my Pygmy Double -- and it's within the means of most people building a boat (I doubt that many builders have access to a spray booth).
I didn't wash rollers or brushes and didn't have a problem -- perhaps I was just lucky.
I suspect that cooler temps would slow the curing time but if it's too long, you run the risk of airborne contaminates landing on the wet LPU -- I don't know that I'd have wanted the process to be any slower.
Proper lighting definitely is important -- you can't have too much light.
Yup, overwork it and you'll see lots of brush strokes -- working quickly with deliberate actions makes the application easiest with the best results.
Dave, I agree about a separate discussion regarding the application of LPU -- I've thought that we should have a section for this (and varnishing) in the Building section of the site. When I've got some extra time ( :roll: ) I'll put something together.
Dave, the big syringe is a great idea for dispensing the LPU.
I've now updated the build journal with about 70 new photos with descriptions. The updated photos start on page 7:
http://www.westcoastpaddler.com/buildin ... =15&page=7
Currently, the boat has been wet sanded to 400 grit. Today, I'll wet sand to 1200 grit and then buff and polish the entire boat this weekend.
It's gorgeous Dan, are you hand sanding with a block? :shock:
After applying the LPU I sanded lightly with the ROS using 220 grit sandpaper. After that all sanding was done by hand using a block -- it goes pretty fast if the initial surface is smooth to begin with. It took me a total of about 5 hours to complete the sanding.
Quite honestly, I kind of get into a groove and don't really mind doing the sanding thing.
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