Jib without the camberspar

Bill
Posts: 18
Joined: Wed Aug 05, 2020 6:57 pm

Re: Jib without the camberspar

Post by Bill »

I will trace around my spar
And photograph with a tape measure
Please send your address to billharvey1355@gmail.com and I will post the tracing
Bill

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mike cunningham
Posts: 489
Joined: Sat Dec 20, 2008 11:21 am
Location: Jacqueline, F30 #3, Discovery Bay, California

Re: Jib without the camberspar

Post by mike cunningham »

Stephen_H wrote:
Sun Jun 04, 2023 12:32 pm
I measured the curve from my camberspar when it was off the F30 I previously owned, and had the attached made by a machinist shop. I had it made from Sch 80 aluminum pipe with the theory to increase strength, but that was a mistake because it ended up too heavy. I would stick with Sch 40 if I did it again.
Good to hear from you Stephen. I still have the tank in my garage :)

Thanks very much for the drawing. I get the chord (76.06 inches) and I can visualize the point of max camber identified by the arrowhead.

I assume the 35.54 and 42.42 inch lengths represent the actual length of the cambered spar to the deepest point and, thus, the total length of pipe required. Correct?

What do the R80.8 and the R157.47 represent? Do these define the camber?

Finally, how was your replacement bent? Does this PDF profile provide all the data the "bender" requires and what kind of shop actually does this stuff? Typical machinist or a specialty bending shop or??
Mike Cunningham
Freedom 30 (Mull) Hull #3
Build date...June, 1986 . Freedom Yachts USA, sloop, shoal keel
Gun Mount and pole retrofitted (purchased from a Hoyt Freedom 32)
Yanmar 2gm20F , 1600 hrs fixed two blade prop
e-rud and ocean racing equipment

Stephen_H
Posts: 35
Joined: Fri Apr 13, 2018 6:35 pm
Location: Port Washington, NY

Re: Jib without the camberspar

Post by Stephen_H »

Hi Mike - The 35.54 and 42.42 are the arc lengths of the two sections. So, yes, the actual length of pipe. The R80.80 and R154.47 are the radii of the two curves. So, the foreword section is a 35.54” arc length of a circle with a 80.8” radius.

This was all the info needed for the shop to bend one. My understanding is they use a pipe or tube bender to create the curve. They do one section then the other starting at the changeover point and working toward the ends. They actually bend a longer piece and cut off the ends to the right length to get a clean cut. I ordered mine from the Metal Supermarket store in Everett, WA. With powder coat it was $537 to have made in 2019.
1985 F39 Express (Hull #44)
S/Y OXYGEN
Port Washington, NY

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mike cunningham
Posts: 489
Joined: Sat Dec 20, 2008 11:21 am
Location: Jacqueline, F30 #3, Discovery Bay, California

Re: Jib without the camberspar

Post by mike cunningham »

Thanks very much Stephen. Appreciate the info.

A long time ago you saw a photo of my boat and mentioned you thought the stowed jib was awfully low to the deck. I sort of ignored your comment thinking this was more the nature of the photo than the jib, but surprise surprise, when I figured out how the spar actually worked, got it rigged properly and got some of the bend out so the chord was approximately correct, the spar and sail are nicely off the deck when stowed. This repair also eliminated the more serious issue of spar over rotation when the sail was dropped causing it to wrap around the jib and force a trip forward to get the sail back up.

The current state of affairs is the spar is unbent (not perfect) and I plan to go out to do some testing. If all is well, good, but if I notice issues re the sail shape I will be thinking about fabricating new and the shop in WA.
Mike Cunningham
Freedom 30 (Mull) Hull #3
Build date...June, 1986 . Freedom Yachts USA, sloop, shoal keel
Gun Mount and pole retrofitted (purchased from a Hoyt Freedom 32)
Yanmar 2gm20F , 1600 hrs fixed two blade prop
e-rud and ocean racing equipment

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