Thread: Curlew

Originally Posted by Daddles

Who's the ugly bugger holding it all up?

Richard

Actually made me think of an old style playboy centrefold - except not horizontal and without staples.

Shirt off, standing in a field of flowers ...

grrrrrrrrr rrrrrrrrrrr rrrrrrrrrrrr

MIK

Enough of this innuendo! (Anyone know the the word for "a spanish suppository"?)

Back to work today so progress will slow.

All ready now to sand and tape the outside.

Main task yesterday was to develop the stuff about joining the two halves together.

Join1 (pic below) shows how closely the two halves butt togther (the best side , the other side isn't quite so good, so why would I photograph that?).

Join2 shows the registration system.
1. The circular plug fits into the circular socket to prevent movement on the vertical and lateral axes.
2. The square plug fits into the rectangular socket to prevent twisting on the lognitudinal axis. (The square into the rectangle is to prevent registration problems due to expansion contraction differences between the two parts)
3. The plate and "hook" on the bottom is to hold the two parts together and allow assembly in the water (yet to be tested ). The hook fits into a groove on the aft section. When nested the plate fits into the stowage compartment under the centre thwart.
4. Lashings (on cleats at each gunwale) will hold the top sides together.

Hmmmm! I see I've left myself wide open to disparaging comments about axes, chopping in half, etc. Ah well, Can't be helped.

Next main job (after the boring sanding stuff), fitting the gunwales. I just borrowed a bunch of clamps......

You know, a couple of F-clamps to hold the two halves together may not be such a bad idea either. Seriously. Or maybe just a bolt and wing nut through the plugs. I'm imagining all sorts of ways for the halves to work against each other and apart. Maybe I'm just a worrier. I'll be interested to see this in action. You aren't planning to bring her down for Goolwa are you?

The folding Schooner Mik, that is hinged at the keel isn't it? So the two halves are permanently hooked together?

Richard

Many observers have made similar comments, however....

I am trying to avoid locking the bulkheads together as this would seem to me to apply too much stress in a direction that might eventually rip them out. With my approach the bulkheads are really just dams to keep the water out and to ensure alignment. No stress on them at all. I think the main stress will be that trying to bend it in the middle. For this I need longitudinal strength which I think comes better from lashings on the sides. (We'll see! No doubt this thread will continue well after launching day, for the entertainment of all.)

Even if the hook on the bottom pulls away, or breaks (and I don't think it will, I've engineered it very carefully), the two halves might just flap about a bit, but will still have integrity as watertight hulls. If the bulkheads give way integrity will be lost. If the hook does turn out not to be strong enough I will replace it with a stainless steel one.

We have some experience of this concept with the boat I designed for the Rough & Ready competition at the Caloundra Regatta http://www.profitworks.com.au/Rough&Ready/ which included much discussion about the likelihood of our 26 footer "snapping" in the middle. It didn't, even with four crew paddling flat out! On that boat we left the bulkheads clear and used plywood straps on the sides to hold the two halves together.

A friend of mine has a Bolger folding schooner and I have sailed with him a few times. Great fun by the way! The hinge is much more important there because the boat is long, has a mast on each section so the twisting moment is greater, and goes fast. The hinge is very much engineered into the structure of the hull and I don't have room for all that structure. Bolger still uses lashings to pull the two halves together (plus bolts and wing-nuts). I am also prevented from using the hinging approach because it won't allow for the two hulls to be nested.

Actually, the Bolger folding schooner friend is also a very experienced engineer. He came up with the idea of the registration plugs and lashings and I was convinced.

Ain't this fun. Nobody has any idea how, or if, it will work.

It's a fun exercise alright. I hadn't twigged that you were lashing it together (don't point out where you explain that, I feel bad enough as it is) and lashings certainly seem a sound way to go.

The hinge could work, if you decide to go that way for some obscure reason (such as it'd make the whole thing hard to use - hey, I use that excuse all the time ... in retrospect). All you'd need to do is engineer the hinge so that you slide one half sideways off the pintles. But yeah, you aren't doing that are you.

Gawd, I'm rabbitting on and it's mid afternoon. Maybe I need a nap.

Keep us posted on this fascinating project.

Richard

Originally Posted by Daddles

engineer the hinge so that you slide one half sideways off the pintles.

Ahhh! Now there's a thought. Our pool fence has a gate with "lift-off" galvanised hinges. A bit heavy for this job, but I'm sure I could get smaller ones. Maybe stainless.

I'll ponder that one! It creates a couple of new challenges that I'll have to figure out to do with nesting and fitting in the caravan. Also depends what is available in the hinge line. Off to Bunnings.

Watch this space....

Originally Posted by Daddles

You aren't planning to bring her down for Goolwa are you?

I really want to get to Goolwa one of these days. Too hard at the moment to make time to get away with boat (and possibly caravan).

Originally Posted by Daddles

All you'd need to do is engineer the hinge so that you slide one half sideways off the pintles.

I called in to Glascraft marine today and they had some hinges that would do a neat job of this. The idea had never occurred to me before.



The only snag I can see is that, if possible, I would like to be able to join the two halves while floating in deep water. This would be useful if it was used as a tender on a cruising yacht. Ideally you could toss the two halves over the side, jump in the aft section and "hitch-up" the bow section. Given that these hinges would have to be on the bottom that might be quite difficult.

Anyway, I have had a bit more of a play with he present system and I think it's OK. If it breaks I will use the separating hinge idea. Thanks Richard!

Today's efforts...
Laminated and fitted the starboard side rubbing strip tonight. I found a couple of things helped.

1. I pre-drilled holes for temporary screws to ensure that, once it was slippery with epoxy, it all lined up correctly.

2. I tied the laminations together with a few copper wire ties while I was fastening them to the skin. This stopped it flopping around too much. Once locked in place I just pulled the wire ties out.

3. Lots of clamps! If they weren't mostly borrowed I would make this my entry in the "He who dies with the most clamps, WINS!" contest. Once all the clamps were fixed and the epoxy had partly set I removed the temporary (steel) screws.

Originally Posted by Boatmik

I had to get you a prompt reply so that the boat will be nice and light but still strong enough. Nothing worse that a boat where some bits are heavier than needed!

OK, well I had originally calculated the total weight to be about 25kg.

I just weighed her (on the bathroom scales) and she' a bit over.

Forward section = 10kg
Aft Section = 20kg
TOTAL = 30kg

Not too bad. I have yet to fit one or two skegs, and some rowlock blocks.

Several small tasks completed today.

I decided to test out the lashings. I think they'll be OK. It feels really strong. All depends on how it feels punching into waves with the outboard.

Just messing about when I need a break from the monotony of filling/sanding.
I've decided not to fit inwales because it will make nesting more difficult, and add more weight, and nesting would make fitting inwales more difficult.

Seems strong, and rigid, enough with just the outwales and it nests together really neatly.

Note plastic cleats for lashings to hold the two halves together. I just stuck them on for the photo to annoy Daddles. Of course, wooden ones would have been much nicer but I have a deadline to meet!

Missed those pics from a week or so ago.
Looks great (plastic and all )

Ever since you started this thread it reminded me of something else I saw whilst poking around some time ago. I found it tonight. They've outdone you ... this one's in three pieces and can double up as a picnic table and baby bath

http://www.svensons.com/boat/?p=RowBoats/ThreePieceBoat

Looking great... inspiring ... hmm

Originally Posted by onthebeachalone

Note plastic cleats for lashings to hold the two halves together. I just stuck them on for the photo to annoy Daddles. Of course, wooden ones would have been much nicer but I have a deadline to meet!

Richard will not be impressed mate Yer askin for trouble postin plastic cleats matey... I mean comeon!! How longs it take to whack out a nice wooden cleat eh? Buggar all time!!! mere minutes in fact ... so next time... bedda be some fine wooden cleats shown by gar or over the bloody side you go boyoh!

And Ramps? You are about due for a new project eh?!! KARMON AUSSIE DAY!!

Haven't really had a good lot this project mate but, I may have taken on a bigger project but yours has some very interesting challenges.
I think your method for connecting the two halves is good, my only suggestion is maybe a Hi Field Lever on either side to ensure that the halves can work around when out on the water. I just think that lashig will definently hold it but its the movement that may cause dramas.
Thats my two cents worth on the joining system, thought everybody else had so.........!
Shall keep watching with interest though, she looks good.
Scotty