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CS17 #260


ecgossett

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For pulling the bottom panels together a very good method is to use a light line, perhaps 3 mm, with a type of spanish windlass. Drill holes about  25mm on either side. Pass the line through and up and tie with a reef knot. Insert a stick or something similar (I usually use a small screwdriver) and twist the line to increase tension. This will pull things together nice and evenly as the line has gone underneath as well as on top. Tuck the end of the screwdriver under the tensioned line when you have pulled it together.

For the bulkhead I agree with PeterP- fit a batten to the lower edge of the bulkhead and then screw through it to the bottom.

Peter HK

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Assuming that your temp middle frame is PERFECT (remeasure it) your second picture implies that the bottom panels are too wide from center to gun'l and the gap you show kind of suggests that the bottom panel width in the area of the gap is closer to being correct that where the panels are butted tight.

If I had that particular situation (and I don't)...

(1) I would not FORCE things to fit by any means.

(2) I'd run a saw blade or jig saw along the centerline where the panels touch

(3) I'd do this until the gap in between bottom panels disappears AND the gap under the temp bulkhead is gone (I'd want the bottom panels to align along the temp frame without having to force the issue.

My 2-cents (before deflation)

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Edward,

I would leave it as it is, folded boat building is not absolute. As I have said before the centerline of the bottom is a very subtle curve and small deviations can make the deadrise or V in the bottom change as much as yours is off. You can't force the bottom up to the temp frame without removing some wood down the centerline. I would look at the keel line from under the boat and see if there is not a bump in that area. If your keel line is sweet and fair then I would ignore the the gap and carry on building. If you feel that there is a local bump then I would remove the ties in that area and remove enough wood to make the keel line fair.

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  • 1 month later...

The plans are not really specific regarding the mast as to what lengths each different size of aluminum should be that make it up.

Any thoughts?

Second question, Graham had mentioned using 10ounch cloth on the bottom and 6 on the sides... I've read some people just use 6 on everything... Any experts in this field or personal experience?

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Re aluminium, I had difficulty getting the right sizes and alloy/temper so had to get it delivered from some distance. Costs for delivery were quite good up to 8 ft lengths but longer pieces were much more expensive :shock: 

I made my masts from two 8 ft lengths and adjusted the wooden topmast length as necessary :)

Doing it again, if I could get longer pieces of tube easily I'd probably use one 10-12 ft tube of aluminium and go straight to a wooden topmast (birdsmouth a good option).

Re fibreglass, when I spoke to Graham in 2006 he said about half of the boats had been built without glass sheathing, but the glass covered ones coped with knocks much better. I used 200 gsm cloth (the approximate metric equivalent of 6 oz) as a balance between light and tough. As a rough guide coating with 6 oz would add 4kg (9lbs), 10 oz nearly 7kg (15 lbs)

Cheers

Peter HK

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I used an aluminum lower with a birdsmouth upper. I made the lower sections long enough so I could take advantage of some nice clear, but fairly short (8') spruce I had. The main was 12' 8" with an 8' upper section (12" bury in the lower section) and the mizzen similar. I was able to get 24' sections of  6061 locally, so this was possible at a reasonable cost.

I also sheathed the exterior of the boat with 8 ounce. The seats and sole were also sheathed with 8 ounce to accept wear and tear.

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'Lively' is not sheathed except where called for in the plans, i.e. where panels meet.  I painted her with System Three two part primer and final coat.  She has held up very well over the 3 or so years I have sailed her.  That paint takes a lot of abuse.  i also used it on my previous tri 'Bananas' with good results.  I do not baby the boat.  I pull her up on beaches, etc.

The big advantage to this idea is much lower weight.

That said, i think on my next boat I will probably use 6 oz glass on the bottom only.  I may use a polyester which is much more abrasion resistent.

Dale

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That said, i think on my next boat I will probably use 6 oz glass on the bottom only.  I may use a polyester which is much more abrasion resistent.

I don't know about the abrasion resistant part, but using polyester will definitely increase the chance of the cloth delaminating from the plywood.  I will never use polyester for plywood boat building in any application.

Both sides of the subject of sheathing in cloth have already been mentioned.  You have to decide whether you want more rugged at the cost of weight or not.  If I were to sheath anything, it would be the bottom only.

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I assumed the same Mike and one of the modified acrylic fabrics (like Xynole) could also be a choice for greatly improved abrasion resistance. Given a choice between the two, I'd use Xynole if it was in the budget, as it's considerable better then the polyesters. Both are way better then regular cloth. Dynel is about 20% more then regular 'glass fabric and Xynole is considerably more, though it doesn't take much to cover the bottom of the boat. It should be noted that neither adds any strength to the structure, just much better abrasion resistance and waterproofing.

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Since most (emphasis on "most") abrasion occurs on the chines and keel strip, wouldn't a strip of kevlar felt (not cloth) along the forefoot/keel and some strips of extra glass or xynole along the chines offer the most protection, and being in strip form, offer good bang-for-the-buck, no pun indented.

Just curious why you'd choose to sheath the flat areas more than the angles, where wear is far more concentrated.

For sandy beaches, I've had to deal with paint/finish scratches on the flat areas, but nothing that extra cloth of any sort would have prevented. It is the chines and keel/forefoot that have taken the brunt of boat--to-land meetings, especially on coral and gravel.

Good luck finding the solution (i'm following along and taking notes...)  :smile:

pat.

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Nope, no erster beds here... just sandy/gravelly beaches and occasionally getting hung up on an old reef flat. If the bottom's that bad, I agree, I'd cover everything, probably twice. Luckily I don't have to intentionally haul a small boat up on that kind of bottom.

I suppose I didn't express my thought well enough, and might try again: just like my knees, toes and elbows, I have noticed that my hulls' forefoot and chines have taken more than their fare of scrapes, compared to anywhere else on the hull, hence I'd likely concentrate the abrasion resistance initiatives in those areas. Especially if oysters are on the menu.

:P

pat.

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  • 7 months later...

Had some friends over today and flipped the hull to work on the bottom... In the process had to drill out some busted screws that had held the inner keel while epoxying... On the good side, discovered with the hole drilled that my job of planing the inner keel to fit was a very close match, with almost no filler gap in-between.

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  • 1 month later...

Fiberglassing bottom:

I'm planning on using 10ounch fiberglass on the bottom.. Should I install the keel first then glass, or glass, and install keel on top?

Planning on this next week when I'm back in Georgia.

- Edward

Having glassed a few hulls (not CS hulls, next on my build list), my sequence is glass the entire hull with 6oz cloth and then epoxy/glass the chine/keel tape strips on top of that, and THEN attach the various parts as in keels and outwales AKA rub rails.

Reason: It's a bugger-bear to run a large sheet of fiberglass over a hump as in keel piece. Placing the tape on after full glassing means you can scrape and sand and fair the tape edge strip in without fear of cutting through a glass layer and compromising the strength of the layup.  With full sheet glass over tape, when you scrape & sand you will cut through the top glass layer = bad do-do.

Caveat: I'm leaning toward  CS-15 and probably will not glass the entire hull. Why CS-15? Quote Graham: "The smaller the boat, the bigger the adventure!"  Besides I will most likely be single handing and I figure a little boat will be easier to get upright when I dump it.

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