Saturday, October 8, 2011

Seasons changing

Everything is back up and running, and I've notched a few more successful outings.  I had my first windy trial this week.  It's a small lake so waves were not bad, but it was maybe 25 mph gusts.  After getting so used a catamaran, I admit it was a little unnerving at first to feel the wind rock the boat.  By the end of the day, I was much more comfortable.  It will still take some getting used to, especially when I do hit some bigger swells.

All things considered, I would have to say the project has been quite a success.  There are a few bugs to work on, but I've had fun on the times I've been on the water.  Hopefully I don't make anything worse when I take it apart to sand and varnish in the spring.  I'll work on some of the bugs before I put it back together.

The first priority will be the gearbox.  It is currently fine for cruising, but not for anything needing more power.  I suppose I am glad I opted for less expensive straight bevel gears rather than spiral gears.  If the box isn't stiff enough, the more expensive gears would have met a similar fate: worn, rounded teeth.  I have some thoughts on reinforcing the housing with cross pieces and also cover plates with a lip on the edges to help prevent pedaling forces from flexing the housing.  If there is an improvement, maybe then I will upgrade to spiral gears.

Next up is the prop.  There is a yet unexplained difference in speed at a given blade pitch compared to calculations, so I have had to modify the blades to make things work well enough.  I suspect my first attempt will simply be to remake the blades and attempt a more accurate foil shape when grinding.

I might also go ahead and replace the full shaft, I'm not sure.  It isn't that expensive, so it might be nice to try one that wasn't accidentally bent before assembly.  I'm still undecided about the drive leg.  There are several options to increase the strength of the chain loop.  The current setup can handle more than the gearbox, and I think it would be fine for distance race speed, just not short full sprints.  I might also try a leg fairing that slides over the drive leg tube rather than move with it.  The steerable prop is nice and it works well, but I think it limits my options on making the chain loop stronger.  I doubt I will decide until spring.

On the boat side, I don't think there is much I would change.  During the design I wasn't sure how far I would place the gearbox from the seat to fit my height.  My other boat has a profiled recumbent seat and this one has a sharp angle, so comparing the two was difficult.  Now that it is set up, I can see I could have shortened this about 3 inches and decreased the windage of the gearbox support.  There might be a few other changes to reduce windage, but it all amounts to fine tuning.  I have modified the stabilizer mount: reattaching the two halves and I also added a cross pin between the vertical pivots to reduce flexing.  It has made a big difference, so for now I will leave this alone.  I really like the vertical adjustment and the ease of setup when launching.  I imagine starting over I could shave off some weight, but it would again be minor changes.  As I mentioned before, in a new boat I would probably make the stabilizers out of foam sheet and also reconsider the weight of cloth in some areas.  It might all amount to about 5 lbs.

Last but not least, repurposing the trailer for the cat works OK, but I will eventually make or buy a better setup.  Ideally something small I could stow on the boat, so I wouldn't even need to walk back up the shore when launching.

In the mean time, the garage needs to be turned back into a garage.  I don't think I would get much support for my hobbies if it meant scraping frost off the car windows.  I've already put the cat up in the rafters and cleaned up my tools and mess.  Hopefully I can get out on the water again before the cold water deters me, but there is a chance this is it.  At least the outing this week was a nice sunny (but windy) day with fall colors.

Hopefully some of the people reading have a nice warm shop or are just getting ready for summer!  If you have a project, it would be great to see it.  Turns out this blog stuff is pretty easy...

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