Thread: Nice rowboat, nothing fancy.

Yeah that makes a lot of sense, and I have thought of it. So far I'm doing well for bugs and dust though (famous last words). Only had three small bugs this morning, and bugger all dust that I can see. The boat is in the carport, which is closed on three sides, and it hasn't been blowing into the carport. I'm also not painting after dark, due to the crap lighting, and have the carport lights off after sunset so bugs won't be attracted. I could rig up a plastic tent arrangement but it'd make working here a nuisance, and it's just another thing to build at this stage, and I'd run the risk of dust and crap being introduced while setting it up, or dropping the plastic on the paint.

Since I'm planning on rubbing back the final coat anyway I'm not too worried. I have a theory this is why the bugs have been minimal: they know it's not worth their while.

While I was waiting for the paint to harden up some more for recoating, I did a bit more work on the rowlocks.

Back on page 12 I posted about how I'd converted them from closed to open top, to suit my preference. Anyway, the face the oar will bear against on the pull wasn't quite flat in plan view. Due to the vagaries of plastic casting, it had a bit of a rise in the middle and at each outer edge, with a shallow dip between the middle and the two edges. I figured this would be better if it were actually flat.

Also, the shape of these rowlocks has a V section at the bottom, intended to give good bearing for the oar when it's tilted so the blade is in the water. The upper edge of this was a bit sharp for my liking, and for some weird reason the V was carried up the rear face of the rowlocks, even though this serves no purpose and gives the rear face of the oar a point to ride on instead of a flat surface.

Since these rowlocks are polypropylene they are easy to work. I got busy with a half-round wood rasp (carefully) and flattened the front and rear faces, and slightly rounded the point of the V at the base of the rowlocks. This looked pretty rough, with rasp marks everywhere, so I got some 80 grit and smoothed them off some, then went to 150, then to 240, then 360. Then just for the hell of it, steel wool. Sounds like a lot of work, but only took a minute or so for each grade for each rowlock. This left them looking pretty decent. Basically as good as the original semi-matte cast finish.

The polypropylene is quite hard, and I like quiet rowing. I figured a bit of leather between oar shaft and rowlock would be good, just to take the edge of the sound and protect the oars a bit. Normally people leather the oars, but I quite liked them without and thought I'd leather the rowlocks instead. I first saw this idea in Wooden Boat mag years ago, and the author said it worked very well. It makes sense, since the oars will be protected even when drawn in through the rowlocks, rather than just being protected while actually rowing.

Ok, so now comes the cunning bit, which may or may not work since it is entirely experimental. How to leather polypropylene rowlocks? Polypropylene is notoriously difficult to get things to stick to, but there are some new glues which claim to do just this. So, I got me some of this here new-fangled glue and leathered my rowlocks. I didn't bother doing the whole thing, just where I thought it was needed. This leaves just enough clearance inside the rowlocks for the oars to be feathered.

The stress on the glue lines should be low, so there's a good chance they'll stay stuck for a while. If they fail at some point it's no big deal. I'll either stick them on again or think of something else. I thought it was worth trying though. Might learn something.

The glue is claimed to be water-resistant, but is not recommended for continuous immersion. In my experience, rowlocks rarely get wet anyway. If they get wet, it usually means you are doing something wrong. Just to help the look of the filed and sanded rowlocks, and to cut friction, and to maybe keep that water-resistant glue line a bit more water-resistant, I threw on some of the same wax that I'll be using over the rubbed-back enamel. This stuff was originally made for gun stocks but is also fine on leather, and apparently has been used for water ski jump ramps, of all things, so it's supposedly fairly tough. The manufacturer wasn't sure how it would go on a rowboat, although she had tried it on her car, so I said I'd give it a whirl and let them know.

Use epoxy on the polypropylene, preferably "G-Flex" from West System. The trick to making it stick is to "caramelize" the surface. What this means is you break up the polymer chains on the surface with a torch, then apply the goo. Wave a torch over the surface you want goo to stick to. A quick sweeping motion is all it takes, you're not trying to melt anything. The heat breaks the molecular bonds on the surface, providing more "tooth" for the goo to grab. You could leave it out in the sun light for a year or two, which will do the same thing, though you'll have to wait a while, for the UV rays to do the deed. G-Flex, because of it's lower elongation properties, will tolerate more flex from the bond line, before it tears off. If you don't have access to G-Flex, make your own by diluting regular epoxy with 15% of less denatured alcohol or 10% xylene. Don't cut it any more than this and use milled fibers and silica in the mix to stiffen it up, so it doesn't run out of the joint.

Ok, well I might try that if the other stuff doesn't work. It comes with a primer, which presumably etches the polyprop anyway, so I'll see how it goes.

Anyway, the final coats of shiny are on now (Saturday evening here). I'll give the outside all day Sunday to cure, and see how it rubs back on Monday. Good drying weather at the moment, so hopefully will be ok after 40 hours or so.

The inside still needs the non-skid patches applied to the bottom, so I'll throw the first coat on those tomorrow afternoon.

Hey I was just reading up on G-Flex and, according to this WEST page, polypropylene is one of the few plastics it won't form a reliable bond to, even with flame treatment.

We discovered that a few plastics, like polypropylene and acrylic and their molecular cousins, are difficult to glue reliably no matter how we prepared the surfaces.

So maybe the stuff I used will do better, or at least as good. Will have to wait and see.

Re surface prep: after the sanding and steel wool treatment I did give the gluing faces a through cleaning with acetone, just before applying the primer pen. It didn't say to do this in the instructions, but I figure too clean can't hurt, and I had some acetone handy anyway.

Par advice is very sound. If you think about panel shops they have a special booth for spray painting so the painting area is dust free. I remember years ago an old furniture maker telling me that painting furniture in the same building as it was made was a no no. He even said it would be several years after cleaning the shed where the furniture had been made that it would be really dust free. When I thought about it I understood why that was right.

Whitewood

Yes I know, however I went ahead regardless. It actually turned out amazingly well. There were no kamikaze bugs at all in the final coat, which must be close to a record. There are some dust specks here and there, but since I'll be rubbing back the finish anyway that doesn't bother me. I could even get away with it the way it is, since straight off the brush it's better than some paint jobs I've seen, but at some point I'll be racing this thing so want the lower drag of a really good finish.

Brushes, even with a good job, leave roughness of 50-100 microns, which is going to give a 10-20% increase in skin friction (at the relevant Reynold's number for racing*) compared to something that is 25 microns or less. Obviously this only applies to the bits in the water, so I could leave the topsides as is, but I'll do the lot just for consistency. It's not a huge area anyway.

*Brush finish would be fine at lower speeds of around 3 knots.

ETA: 25 microns is about the same roughness as 400 grit sandpaper. This would be smooth enough that it would make no difference for most of the hull, since it's what the fluid mechanics guys call "hydraulically smooth". However, if I just sanded with 400 grit it would leave small scratches that would tend to pick up crap and staining, as well as just looking like it had been sanded with 400 grit. So that's the reason for the steel wool and wax plan: not to cut drag, but just to keep the surface cleaner and better looking.

Once I get to 400, I usually just move onto rough polishing with a buffer. Progressively moving through a rough, then fine rubbing compound, then real polish and eventually wax to condition the finish so it stays reasonably clean. This process doesn't take a lot of time, maybe an hour with each buffer pass, but the end result is a high and conditioned luster. It makes you look like a pro, even if it was some buffer time and a few globs of goo in a tube.

Righty-o then. The last bits of paint are officially on the boat!

Just threw the non-skid patches in. They've only had the one coat, but with the grit added there's a good build up so I reckon one coat will be adequate. Can't be bothered adding another one at this stage, so the boat is now painted.

I used the same enamel as the exterior, just with some gritty stuff added (White Knight's "Pave & Deck Grip", because it was what Mitre 10 had and it'll do the job). The instructions say 2-3 scoops per litre of paint, and I was mixing about a third of a litre, so I threw one scoop in and mixed it up. It looked a bit weak on it, so I threw in another scoop. This gives a good texture, IMO. It's a fairly fine grit anyway, so the extra scoop wasn't overdoing it. There's about half the paint I mixed left over, so I'll store that for touch ups.

I reduced the size of the non-skid patches over what I'd originally planned. Instead of one width of masking tape from the frames and chine logs I used two widths, slightly overlapped. This lines the non-skid patches up with the limber holes in the frames, which looks neat, and cuts the amount of interior green down to an easy-on-the-eyes level so it doesn't grab your attention compared to the wood. Visually it's much better this way, compared to what I marked out before, and the resulting patches are still large enough to deal with any feet that are placed where feet ought to be in a boat like this.

There's still a little bit of cleaning up to do here and there, plus the rubbing back and waxing, but hopefully I'll get that all knocked off tomorrow.

Originally Posted by PAR

Once I get to 400, I usually just move onto rough polishing with a buffer. Progressively moving through a rough, then fine rubbing compound, then real polish and eventually wax to condition the finish so it stays reasonably clean. This process doesn't take a lot of time, maybe an hour with each buffer pass, but the end result is a high and conditioned luster. It makes you look like a pro, even if it was some buffer time and a few globs of goo in a tube.

Me no have buffer. Have 0000 steel wool.

I reckon, based on a couple of quick test pieces, that I can go straight from 360 grit (aint got 400) to the wool and get away with it. If necessary, I do have a few sheets of 600, which I'll use if it seems like a good idea.

Come to think of it, I also have a tin of Polyglaze Cut & Polish stashed somewhere. Not sure if that would be a good idea though.

Got some final weights this morning, since all the paint and oil is now on.

The bare hull is exactly 28 kg (61 lbs 11 0z).

Hull + main thwart + footrest is 30.4 kg (exactly 67 lbs).

Hull + main thwart + footrest + oars is 33.9 kg (74 lbs 11 oz).

The last number is minimum race weight, plus me of course for actual displacement. Me is currently heavier than ought to be, but will work on that. However, as weighed this morning, including jeans, belt, t shirt and wallet, I'm 83.4 kg. This will put the boat about 1 mm below the (salt water) DWL I used when designing, so that's close enough. Once I'm back in shape I should drop about 10kg off that.

Should also be able to save about a kilo with a better set of oars, and could trim footrest and thwart weights if I really wanted to, but as is it's pretty damned good.

I'll give the non-skid paint a bit more time to cure (overnight isn't really enough for oil-based) but will probably throw the thing in the water tomorrow.

Today I got to thinking. I'm not currently fit enough to race the thing, and the races I have in mind aren't for months anyway. That being the case, why do I need a racing quality finish now? It's likely to get dinged up before the races, while I'm getting the hang of transporting, launching and retrieving the thing, so I'd probably need to go over it again in a few months time and make it all shiny again.

The finish straight off the brush is decent enough, and what I really want is to go rowing.

Also, I'm kinda over sanding at the moment.

So, stuff sanding the bloody thing. Today I spliced up the painter (tapered splices and all), as well as making lanyards for the rowlocks, the footrest, and the totally awesome bailer (the ubiquitous 2 litre milk jug with the bottom cut off - a great Australian tradition). The lanyards are done as loops (or eye splice in the case of the bailer lanyard) so that attaching or removing things from the boat is a simple matter of putting the item back through the loop and then pulling the lanyard clear of the limber hole. No tying of fiddly knots with wet hands required.

I also cut some strips of carpet to fully pad the cradle, and glued those on with urethane glue, which is going off at the moment. Current cunning plan is to get the boat and cradle on top of the truck tonight, then go looking for water in the morning.

Go get 'er wet man . . .

Rowing sounds like the right thingto do now,, probably fun as well,, been a fun thread thanks. looking forward to the results.