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I have built the gaff for my T30. Looking at the almost finished spar I am asking myself if I should give it some taper towards the end. The gaff is a 5x7cm spar laminated from two 2.5x7cm pieces of fir. I have just rounded the edges but not taken off much wood. I take it it is not mend to be fully rounded.
There is nothing in the plans about rounding or tapering but it could save some weight aloft.
What would be the right thing to do?

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I would go ahead, however the main weight is the gaff itself not the claw. I had seen a solution where the wooden gaff was laminated in an aluminium tube, which probably saved a lot weight.
Do you have som pictures?
Unless you are worried about the aesthetics, I wouldn't worry about tapering the gaff. I rounded the gaffs for my 38 just enough to allow the sleeve to fit over them easily, and haven't been sorry I didn't do more. I can't imagine that tapering the gaff would save any significant amount of weight, or that any weight saved would matter for speed or stability. If you were serious about saving weight you could have buit the gaff out of spruce rather than fir. The untapered gaff will be a little stronger (perhaps) and perhaps a little easier to get down when pressed by the wind. You have enough to do when building so save a little time here.

Thank you Bjoern and Ron for your input. I have added some pictures of the gaff as it is to my picture collection on my site. Please have a look. The weight of the unpainted but otherwise finished gaff is 4.9kg now. I do not mind the extra work of tapering, that is a matter of minutes, my concerns are mostly with the strength of the spar.
Nice shots you posted. Personally, I would leave it at that and start glassing because:
1) It's aesthetically pleasing as is.
2) It's stronger now than it would be tapered.
Tom, thank you for the encouraging comments on both gaff and bucket WC.
I think I will wait until I get my mainsail and see how easily the gaff slides into the sleeve. If that works alright I will most likely leave it as it is.
I left my T-30 rig gaff not tapered but I did have a problem with that pivoting foot in the middle of the claw that the halyard attaches to. As I peaked the gaff the radius travel of that foot reached its end and then the gaff started to push away from the mast causing tension on the luff pocket creating all kinds of problems with sail shape. My gaff was exactly to plans and looks exactly like yours, so check the rotating travel of that foot and make sure you can get the proper angle peaking the gaff. I had to notch out the back side of the foot to clear that bolt dowel directly behind the foot.
Frank, Thank you for the advice. I can see a problem developing around the pivoting angle of the tumbler. Actually I thought about it before, than double checked the plans for measurements and found it to be just right to plans. I actually may have a problem there. Thanks again for the hint.
I would check it on the boat. My 38 gaff's and sliders were built exactly to plan and the sliders proved to be too small and did not contact the mast. This put all the weight on the jaws, which then had a tendency to bind, making the sail almost impossible to get up or down. I ended up moving the pivot hole to the back of the slider, and then adding another three-quarters of an inch to the slider itself. (I think the reason it didn't fit is that the mast was built to the maximum size, then glassed and painted. The glass and paint probably increased the mast diameter enough to cause the gaff jaws to be in effect too small, and push the slider away from the mast. The masts also were very tight fits (involving some shaving of one) in the mast casings. Problems ripple in unexpected ways.) All works better now, but my experience indicates you ought to check everything before you go to sea with it to make sure it all works. The sails can be difficult to raise and lower if there is much friction or binding in the system.

I only glassed the areas around the holes in the gaffs (per plans). I thought about glassing the whole business, but figured it would be time-consuming and add more weight, and wasn't needed for protection. The gaffs are under the sail cover (mostly) most of the time, so the sun really doesn't have that much to work on, and I thought the paint would protect them. So far (almost two years), so good. Again, you have a lot to do so don't over think it.

My slider was the same and had to be made larger. I put a piece of starboard on the side of the slider running against the mast to reduce friction. David www.boatsmithfl.com
I've been using HMDP "tape" on my gaff slider; the kind that comes with an adhesive on the back. I put contact cement on the slider itself, let it dry, and then place the HMDP tape (high molecular density polyethelene, I think!) The ultraviolet gets to it after several years, as it is only 1/32" thick. I just peel off what's left and put a new piece on. The starboard sounds like a good idea: being thicker it would last longer.

Besides observing actual gaff to mast relationships, do make sure you have fair halyards! A twisted block will ruin your day.
Lots of good advice here. When I built the gaff I used a mast 'dummy' - a plastic tube of just the same diameter as the mast should be, 140mm - to make sure that all fits together in the end. I allowed a few millimeters on each side of the jaws for leather or some other protective material and to give a somewhat loose fit for good sliding . If everything fits 'too well' it wouldn`t slide well enough.
All I have to do now, is to build the mast according to plans and not thicker than that.
Besides I do not plan to glass neither the gaff nor the mast. Paint was designed to protect wood from the elements and that is what I will use.
I glassed the masts on my 38, and would recommend it for anyone building wooden masts. They are fairly vulnerable to nicks and dents during assembly, as well as in operation, and they can be hard to inspect in the larger (38 and up) sizes). I used fibreglass cloth woven in a tube, which was not expensive and went on very easily. Paint gives up sooner or later, but the epoxy glass provides a much more stable substrate than wood and is a second layer of protection if the paint starts to go. I can see though, that for the smaller sizes (26 and down) the paint may be enough, as it is much easier to get the mast up and down for inspection and repair.

Of course, if I had it to do again, I would build the masts of alumininum. Same money, same weight, fewer worries.

I have been using leather greased with tallow on the sliders and jaws, but may just screw a piece of 1/4 inch nylon on the slider to see how it works.

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