Sewn-on composite hull fittings

PDQ issues applicable across all PDQ Yachts (or if you can't find a place for something, it probably belongs here for now)
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thinwater
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Sewn-on composite hull fittings

Post by thinwater »

I am thinking of adding a fixed bowsprit to my PDQ 32, but getting to the inside of the bow to attach bolts for any sort of pad eye looks like agony, particularly as I try to get it as far forward as possible to minimize the bending load on the front beam. How about this approach, sewing a fitting, if you will, through the solid glass very near the bow and near the waterline? It seems it would be simple, neat, and strong. Because the PDQ has relatively blunt bows, my actual arraignment would be more forward and probably vertical. The eye need only be large enough for 1/4" high-tech line, so we are talking about a very small protrusion.

The attached image is cropped from a 1991 Multihulls issue - the whole page scan was too big, but I think this gives the idea. The maximum working load seems to be ~ 800 pounds - more than that and you're going over anyway! The compression load to the front beam would be about 500 pounds. I need to consider what support that might require, since the punishment for losing the beam is losing the mast. An aluminum post from the beam to the bridge deck would do and would be simplest.
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Page 83
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Re: Sewn-on composite hull fittings

Post by Page 83 »

Page 83 has a bowsprit and whisker pad eyes near the waterline, bolted thru a backing plate inside, but below the foam coring. Its do-able. The lead angle is critical to prevent crazing around the gelcoat. Take a look next time your by HHN.
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Re: Sewn-on composite hull fittings

Post by James Power »

Hey Thinwater, over the years I have seen the pad eyes fail due to incorrect installation angle as Sandy mentioned, and a backing plate system that could have been beefed up. The system that you saw in Multihulls Magazine looks very interesting, it distributes the load over both hull skins, and since its fiberglass to fiberglass there is no caulked seal to fail. The compression post is definitly something to look into. As far as the agony of installation, I feel your pain. James
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Page 83
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Re: Sewn-on composite hull fittings

Post by Page 83 »

Drew: after thinking about this for a while, I wonder if a problem could arise by the hull skins flexing inward under load. That would result in the bond at the inboard skin being cyclically stressed in two directions. I think the solution would be a spacer between the skins, either something injected into the interior space or a block and goop pushed into place from an extra access plate, then drilled after it sets. That makes it a one-man job. And computing the lead angles should appeal to your engineer's mind! I did it with string and tape.

I use a VERY cheap video-conferencing USB camera [$11.00 !] on a stick to check out spaces I can't see into. It has a led that illuminates in the dark.
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Clever Solutions!

Post by thinwater »

I like both of those thoughts. In reality, I doubt I will go anywhere with the project until I sail her for a season to understand her better, and then lay her up on the hard and stare at her for a while up close... and perhaps with the $10 camera!
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Re: Sewn-on composite hull fittings

Post by jak430 »

I am in the process of buying a PDQ 32 and would like to add a bowsprit as well. Have you gone ahead with the project and could you share your results?
Thanks
John
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Page 83
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Re: Sewn-on composite hull fittings

Post by Page 83 »

The bowsprit is the easy part. Rather than build a strut to brace the forward cross beam, just use a sprit thats long enough to extend back to the bridge deck, either above or below the trampoline. Above means it would be easy to stow when visiting a charge-by-the-foot marina, and putting it under the cross beam means the furler could be lower for a longer luff on the screacher, and leave more room for the bow-bunnies.

You will need at least a four foot slot between the screacher and the genoa luff, or the screacher will foul the flow over the genoa. Adjustable whisker-stays (the lines that go down to the waterline from the end of the bowsprit) would allow you to position the tack of the screacher to the lea side and get a tighter sheeting angle for a few more degrees to windward, as well as get the furled screacher away from the genoa when hard on the wind. My screacher sheets to the spinnaker turning blocks attached to the toe-rail as far aft as practical.

After you rig the bowsprit, test sail with your genoa on it. The important question to answer is whether that much sail forward of the center of lateral resistance will give you lea helm. If it does, a gust could over-power the rudders and make it impossible to head up. Not a good thing. Don't go ordering a 200% drifter until you've made that evaluation! A lot of head sail could lift the windward hull enough to let the high rudder suck air, leaving you with one rudder instead of two! Remember, I've got a shorter mast and two feet more beam.

I lean toward suggesting an under-slung bowsprit because of all the clutter around my over-the-tramp bowsprit. It apparently scared all the bow-bunnies away.....
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No, I have will not start until I finish the season.

Post by thinwater »

I have noticed that with the ~130% genoa there is still considerable weather helm on the 32 when going to the weather, when the breeze pipes up. It seems to be relatively neutral with the chute.

But Page 83's comments should be taken seriously. The rudders on the Altair seem to be just big enough and could be overpowered.

My intention is to simply rig up a temporary pole, similar to Page 83s and see what I think of it. I don't really like the clutter, but it is the most practical answer. Also the length matter is real. Many or most marina will charge you for the 4' for EVERY service. I have NO intention of falling into that trap. It is bogus.
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