beautiful skeleton

[Jeremy Harris]

Thanks again for the kind words. If you want to see the process of trial, error and a certain amount of experimentation that led to this boat, then it's reasonably well documented in this thread on the HBBR forum: http://uk-hbbr-forum.967333.n3.nabbl...td2424625.html

The details of the way the frames were bent on a simple jig, and the way parts are fastened together are in that thread. The stringers, gunwales and keel weren't pre-bent, they were just pulled around the frames, with a single set of supports at the midpoint of the strongback holding the three big tubes in the correct place. The frame was very quick to build, but as always it is the detailed finishing work that takes 90% of the build time!

Jeremy

[portacruise]

Those SOF are really elegant, beautiful boats, real attention getters. Thanks for posting.

Just wondering how these compare with the latest inflatable kayaks in terms of weight and speed. Some can be quite lightweight, stiff and very fast. Fewer worries about bending a frame and punctures with some of the newer materials. Some are self bailing, easy to store and transport. I don't know if they are allowed in the drill challenge. Of course they are generally UGLY compared to SOF, but whatever gets the job best as some engineers like to say... http://www.navagear.com/2008/02/01/a...latable-kayak/
Sorry if this is off topic, move or delete as required....

Porta

[Jeremy Harris]

Just to finish my contribution to this thread I thought I'd post a couple photos of my row in company up the river Hamble yesterday, as it was the first rowing outing for Aero, my SOF self-design aluminium tube boat that appears elsewhere on this thread. We rowed around 7 miles in total, with a break for lunch in a hostelry tucked away towards the top of the river, which was a reasonably good work out for me (and certainly the furthest I've ever rowed in my life!).





She rows well, better than I can row her with my limited skills, but needs longer oars and a few minor adjustments to the position of the seat and outrigger. Overall I think she's turned out to be an interesting experiment in slightly unconventional lightweight boat construction.

Jeremy

[upchurchmr]

Jeremy,

I hope you will contribute one last time.
Are you using a fixed rowing system?
What was your final weight?

A last suggestion - If you can borrow a set of hachet blades I believe you would like them very much.

Looks very nice. Have you had any concern about damage to the skin where you row?

Marc

Marc

[upchurchmr]

Jeremy,

I hope you will contribute one last time.
Are you using a fixed rowing system?
What was your final all up weight?

Just one last suggestion - if you can borrow a set of hachet oars I think you would like them very much.

Very nice boat. Do you have any concern about skin damage where you row?

Marc

[Jeremy Harris]

The weight came out at about 15kg (a bit over 30lbs) which is heavier than I was hoping for but OK. The rowing system is fixed, but all the parts just clamp to a pair of 1" diameter alloy tubes that run either side of the sole, so I can easily adapt her to sliding seat, sliding rigger or whatever. The first mod will be to fit my front rowing system with the same fixed seat, but with longer oars (using the blades I've already made). I have some damage to my neck and yesterday's trip on the river exacerbated this because of the need to keep turning around to see where I was going.

I may try some different blades once my skill level is up to using them. Yesterday's trip was by far the furthest I've ever rowed, and showed me that I need to do a fair bit of practice before better oars might make a noticeable difference!

I'm not at all worried about skin damage out on the water, the stuff is pretty tough and it would take hitting a sharp fixed object to cause damage. I suspect it's as tough as a boat made from 4mm plywood in terms of impact damage resistance. The only thing to watch is abrasion when running up on a beach or riverbank. Sharp shingle will scratch through the paint and risk abrading the cloth on the stem and keel, so I have covered this with a length of 2" wide waterproof polythene tape, the clear stuff intended for repairing polythene greenhouses. This seems to work OK, but is sacrificial so needs replacing when it gets a bit tatty. I found that warming it up with a hot air gun set to a low heat makes it shrink slightly, so that it will then go around the curve of the forefoot smoothly. Polyurethane helicopter tape would be a lot tougher, but it's pretty expensive stuff.

Jeremy

[nordvindcrew]

did you repair your drill powered outboard? It looked like a work of industrial art. I'm interested in how it worked: speed and distance traveled. Have you looked at the thread on weed whacker powered outboards? They seem to have done a lot of work on efficiency to get the most out of a 25CC engine.

[Jeremy Harris]

Originally Posted by nordvindcrew

did you repair your drill powered outboard? It looked like a work of industrial art. I'm interested in how it worked: speed and distance traveled. Have you looked at the thread on weed whacker powered outboards? They seem to have done a lot of work on efficiency to get the most out of a 25CC engine.

Thanks for the kind words, I never considered it to be art!

I have fixed it, but haven't got around to trying it out again yet, as I really only built it for the competition. I may give it a go next time I take the boat out to try the forward rowing system.

I optimised the prop and drive leg gearbox to get the best I could from the limited power of a cordless drill, using stuff I'd learned whilst building an efficient drive for my electric boat (Efficient electric boat). Much of my knowledge of squeezing the last little bit of efficiency from such a drive came from Rick Willoughby's experiments with pedal drive.

Jeremy

[Jeremy Harris]

For those with access to Watercraft magazine (http://www.watercraft-magazine.com/) there is a 6 page article on the design and build of Aero, my "skin-on-tin" boat, in the current issue (September/October 2011).

Jeremy

[DCockey]

Originally Posted by Jeremy Harris

For those with access to Watercraft magazine (http://www.watercraft-magazine.com/) there is a 6 page article on the design and build of Aero, my "skin-on-tin" boat, in the current issue (September/October 2011).

Jeremy

Just read it your very informative and well written article. Nothing was a surpise given what you've posted here but still very enjoyable to read.

[Jeremy Harris]

Originally Posted by DCockey

Just read it your very informative and well written article. Nothing was a surpise given what you've posted here but still very enjoyable to read.

Thanks very much for the kind words. I have another article promised to that magazine on the electric boat, but I'm still refining that so its unlikely to appear before some time next year, I think. As you may have guessed, the editor of that magazine is quite enthusiastic about efficient and affordable electric power for small boats.

Jeremy