TimB
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Posts posted by TimB
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Hi Randii, In the early days some mast extrusions (which is what your beams are) were made in two pieces because the Aluminium company didn't have the capacity for larger dies. So they made some sections in two pieces with a stepped edge so they could be sort of clipped together, then riveted. Later the masts were made in one piece. Some really big ones were still made that way until recently. They are almost all carbon fibre nowadays.
Tb
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Randii, the accepted method for making the sleeves is to buy the same section extrusion as the beam.
The alloy beams on most tenant cats were typical mast sections of the appropriate size.
You cut the bolt rope groove out. This allows you to compress it slightly and slide it into the beam. Usually riveted in place. some glue them as well. Also you need to round off the ends so they do not form a hard point where they finish. .
Tb
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Why is the font so small?
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Try the RV shops for 12 and 24 V TVs.
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Batteries.
Cyclors is too reminiscant of the AC50's.......
Tb
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A catamaran will normally run pretty straight, however it gets hairy and scary quick if you let it get sideways. Boards up and a tiny bit of headsail sheeted centred helps to keep straight, then go warp and drogues..
Most cruising cats have lots of buoyancy forward, to provide room inside.....
Tb
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Seems no one else is concerned or noticed this Martin.
However I do remember the likes of Split Enz and Afterburner have rigging leading to forward ends of their hulls to avoid the windward (rear) shroud pulling the windward stern way up twisting the whole structure, which leads to the rig leaning even more to leeward. Split Enz also had massive rubber things to take the slack out of the very loose leeward shroud.
That's another problem of the GBE style open deck cats and flexible trimarans. I remember Malcolm Tennant taking about "tension structures", ie all the loads are spread around using wires or tension only members, with a few compression members here and there....eg beams and hulls.
Tb
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Squealer, currently in Nelson, contact owner, Stu, at 0272462206, trade me https://www.trademe.co.nz/motors/boats-marine/yachts/keeler/auction-1615542707.htm?rsqid=35980556fde348baa50cd2645ca57711
Tb
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Lizaloni
Are you in New Zealand??
Try and find some Eucalyptus, bluegums such as saligna or botrioides would do. Alternative is River red gum, or spotted gum.
Can sometimes get this as decking timber at Bunnings, Mitre 10 etc
Could also use tropical hardwood also sold as decking.
just machine the grooved side flat and laminate with epoxy to get the required thickness. coat with epoxy for protection.
Don't use Kauri, it is too soft.
NZ timbers such as Matai or even heart Rimu would also do. Can sometimes be found in house recyclers yards.
Tb
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When did you move to the northern hemisphere BP?
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SAF2205 is a Duplex Stainless Steel. there are lots of them. They were developed for the oil industry in the 60's to prevent Stress corrosion cracking in high temperature heat exchanger tubes on oil rigs in the North Sea. Using seawater on the cooling side so hot wet and lots of chlorides.
Much stronger than 316 but must be careful welding not to let the (inter-pass) temperature get too hot or the structure changes and it is no longer duplex. Duplex means the molecular structure is both austenitic and ferritic. 304 and 316 are austenitic.
An another interesting things is that its coefficient of expansion (with temperature) is almost identical to that of mild steel where as 304 and 316 are almost double.
I was involved in building two 30m by 5m diameter pressure vessels (10 bar pressure) for the pulp and paper industry back in the nineties. we saved about 30 tonnes per vessel by changing from 316 to 2205.
Tb
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Wheels,
I thought series connection would be a problem (for a boat based set up) as if one panel is shaded it drops the output significantly, but it not so significant if they are in parallel and one panel is shaded. I have 2 x 150W panels in parallel on my caravan roof and the max current I have seen is about 10 amps, it blew a 10amp fuse so might have been higher once, now have 15amp fuse, didn't want to go any higher and it has been fine. I have a MPPT reg. Keeps the fridge cold nicely even on cloudy days.
Cheers
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I think he means it could be bigger, maybe with the clew back near the rear beam! This is NZ style sarcasm disguised as wit.
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IT, what's a "sennit"?
Rgds Tb
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DR W. The foil is solid bar stock made from Bisalloy 80, a high strength carbon steel. The central piece goes full length with other pieces welded onto the side to give a rough foil shape. Stu got the "design" from someone in Auckland but it stopped at the plate attached to the hull (which was only 16mm thick I think).. I convinced Stu to extend the tongue up inside the boat. The floor design was basically intended to spread the loads from that tongue into the boat structure and avoiding any concentrations. I describe it this way ... compare holding on to the end of a broomstick by one finger and thumb to holding the end in your entire fist.....
Cheers Tb
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Thanks BP. I had a wee chuckle at the comment "slowing down to 7 knots", for most of us that is a target up wind......
Tb
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Hi 830
forgot to do the photo last night ..of course to much fun. Anyway it's not a 7:1 it's 6:1 with a 4:1 fine tune on the tail. So both ends of the mainsheet finish forward, one goes thru the block on the deck with a cleat, the other end goes to a double block which is the upper end of the fine tune. the ends of the fine tune lead port and starboard to a cleat at the seat edge so you hand sort of falls on to it.
hope that makes sense?
Cheers timb
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830
On the Elliott 11m I sail on we have a 7:1 mainsheet (I think need to check) with a 4:1 fine tune. The 7:1 is marginal in any decent wind. The mainsheet traveller is behind the helm and the mainsheet runs along the boom forward and down to a block in front of the helm same as yours I guess. The 4:1fine tune is located just behind the main exit block on the floor of the cockpit. It feeds to both sides so can be adjusted with one hand from the seat. I'll try to remember and get a photo tonight for you.
Cheers
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Hi Dellboy,
Probably best to look at slipping down the east side of Durville and through French Pass, but make sure you get the tide right for the pass. Nice place to stop is Catherine Cove, not to far from French Pass on the North side. Lots of club mornings in there. Once you are through French Pass and into Tasman Bay head across to Abel Tasman. Then the world is your oyster!
Tb
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Pressure and volume are one part of it. How much water do you guys carry? In our caravan we have a 15l hot water cylinder and by using the wet down, soap up rinse off sequence can get two maybe three satisfactory hot showers by turning off the water flow for the soap up part. However it still uses lots of water and soon fills up the grey water tank. We have 160l of fresh and 130l of grey (and the same black). and we can only just go for a week without having to find a dump station. But will have topped up the fresh water somewhere in that time.
Cheers
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Cat 1
in MarineTalk
I think a big issue on modern boats is rudders and for some reason NZ regs don't consider this. In Australia for Cat 2 you have to carry a usable spare rudder cassette that gets mounted off the transom. This is on boats with under hung rudders like most larger keel boats. I've always wondered why NZ is so silent on this, just requiring an emergency tiller which is useless if the rudder is gone sideways below .
The best cassettes use a separate rudder blade like a GBE rudder so you can mount the cassette then slide in the blade once it is attached.
just my 10 cents worth
Tb
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Thanks Rigger, so if built that long ago probably some serious corrosion issues as well.
cheers
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Why did it break in half, incorrectly ballasted perhaps? I noticed they said at the end no environmental issues. Is that because as John Clarke famously said it was outside the environment.?
That was in a skit about a ship off the coast of Australia whose "bow fell off"!!!
Cheers Tb
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slime
in MarineTalk
Scottie said "sh*t - the more you look at her - the more you realise just how much work's been done"
Yes and John is a perfectionist as well as having the skills of a master craftsman, actually,, I suppose you can't be a master craftsman without being a perfectionist........
Tb
Ross 830 Open Transom conversion
in TechTalk
Posted
And vertical not angled out on a leaner???