Transom extention vs. swim platform

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thinwater
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Transom extention vs. swim platform

Post by thinwater »

I really like my PDQ 32. It may be the last boat I own. It certainly has the basic durability, I have determined that I am unlikely to cruise beyond the Chesapeake, and if I do ZTC has proven that is no problem. I like the smaller size as everything is lighter, and my joints arn't getting any better. I like the ease of getting slips.

So what would I fix, if I had a dream list?
* AC. I hate the Cruise-n-Carry, but for now it will do. I will build something in when it breaks.
* New mainsail. Mine has a terrible leach. Easy, I'll order a new one in a season or 2.
* Pitching. Longer is better.* Easier boarding for my wife. She has a fake knee, balance issues, and the nasties ankle fracture I ever saw (right through the joint surfaces).

And that is it. I'm OK with the outboards. I like the kitchen and I like my heat OK (we did a long cruise on 25-40F temperatures this winter and it did fine). I love the aft cabins and I love the 270 degree view from the salon.
______________

I am considering either transom extensions (like Pacifica) or some manner of bolt-on swim platform that will make boarding kayaks and the dingy easier. I really only need a 2-foot extension to solve the boarding problem.

Re extensions. They would be relatively low, like Pacifica's because I do not want the higher sides as on the Seawind extensions; we use the lower steps when boarding from floating docks. Blocking the sugar scoop steps is incompatible with disabled access. The high sides would flow nicely going up wind, but down wind they could catch waves, so although they look pretty, I don't know that they are so functional. The reality is that I will never see huge waves on the Chesapeake.
* Better speed (perhaps), load carrying, and pitch reduction.
* Many days on-site fabricating. I live 1 hour away.
* Difficulty match gelcoat and fairing.
* Increased resale value if done well.

Re swim platforms. These would simply extend the lowest step (about 8 inches above the waterline) aft about 30 inches, bracing off the step and transom lip. The boat would become about 34' overall.
* Could be fabbed at home and bolted on. Next owner could trash them.
* Cheaper.
* Gelcoat matching and fairing less critical. Nothing sloppy, just more forgiving.
* Lighter by far.
* Could do just 1. Might do 2.
* Though there would be no hydrodynamic advantage, I certainly would fair them so that they add no drag.
* Could be fabricated in such way that they are effectively "bolt on extensions."
* I'm more like to overcome inertia and actually do this, rather than put it off.
* No sailing time lost. This counts big.

Your thoughts? Forget structural concerns; I'm an engineer and will get past that.
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amytom
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Re: Transom extention vs. swim platform

Post by amytom »

Drew,

I like the idea of the full extensions. Pacifica did a wonderful job and if that could be duplicated on a 32 I think others woud follow suit. Myself included.

The costs of the moulds and the time spent in R&D could be recovered by selling kits and instructions. (put me in line)


Bolt on extensions always look like an afterthought and don't provide any bouyancy or waterline extension.


I'm hoping you continue and share your results.

Tom
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Re: Transom extention vs. swim platform

Post by thinwater »

All true, and I may go the long route. For heavily laden cruisers I can see the upside. For me, on the other hand, less. Down wind my transoms are clear of the water so an extention is only wieght. Up wind, they are only emersed a few inches. If the bottom sweeps up too far, supporting the ladder will be tricky. One lesson I lerned from my Stiletto is that added weight is to be taken very seriously. If I do add extentions, I'm thinking short is better than long, perhaps only 18-24"... and then it hardly seems worth all the trouble, though small size makes them easier, both fairing and structural (lighter by the square).

Another idea. What if a swim/boarding platform could be hinged, much like the transom ladder, and installed on the other side?

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Re: Transom extention vs. swim platform

Post by thinwater »

After taking a look and a few measurments, I'm leaning toward extentions.

* A mere 18 inch extension makes boarding very easy. A pair of cleats would make securing the tender a snap. The davit is right in front of you, as a hand hold. In rough conditions, climbing down over the back is safer, but that is a separate issue and not relavant to passengers with mobility issues.
* Between the bottom paint and boot top coverage there are only a few inches of gelcoat exposed if I keep them low.
* Though longer extensions would benifit a PDQ 36 (they typically have 6 inches of transom immersion), the PDQ 32 transoms will be just clear of the water with an 18 inch extention if the existing curve is followed. I recall the Pacifica extentions had some additional rocker, which is not hydordynamically optimum.
* 18-inch extentions do not change the docking length of the boat; the tender will still extend a few inches beyond the transoms.

On the negative side, for any project, there is no internal access.

Does anyone know if the 2 transoms are 100% symetrical? It would be nice to build 1 plug from a plywood mock-up, make a top-and-bottom mold, and only do the bonding and finishing on-site. My 1-hour travel time is a factor, plus nearly anything that can be done in a shop saves labor and comes out better than field work; my projects are nearly always things I can pre-fabricate at home.
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Re: Transom extention vs. swim platform

Post by thinwater »

Any reason I couldn't apply several coats of wax to the last 2 feet of the hull and pull a mold of the lower foot (all that I need)? Yes, I would need to narrow the mold by taking a seam down the bottom. I would need to attach the form to plywood staions and glassed-in stringers, but I would get a nice smooth surface with the desired compound curvature; after all, I want to match the rate of curvature. Could save a LOT of fairing and any glaring transition in form.
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Re: Transom extention vs. swim platform

Post by Page 83 »

Short Story:
I had a guest even more rotund than I. Stepping from the bottom of the dinghy up to the lowest step on Siesta (the Atlantic Cat, not the PDQ) was fraught with peril. While maneuvering, I inadvertently let the bow of the dinghy slip under the narrow platform between the sterns. She just turned around and sat down on the platform. Job done. She was aboard, and pleased with herself.

Moral: It's easier for a person to get on a board hanging over the dinghy. Such a device might be a simple platform that hinges down from the vertical face of the aft end of the bridgedeck. You might even look at a few 4WD truck door steps for inspiration/critical review!

Don't let that solution interfere with your hull extension plans. Next time you haul out, set an easel 2 feet aft of the sterns, and trace the beam from a laser level held against the hulls at three, seven and a half, and twelve inches forward of the transom. Interpolate a fourth curve on the traces, and bend a large piece of thin aluminum to fit between a piece of plywood cut to the shape of the transom. and another cut to the resulting extension of the tracings. This will be a simple curve, not compound paint it to match the hull and bottom paint, and examine your results at night with a pinpoint light. You might decide this simple curve is adequate, or sculpt some bondo to duplicate the curvature of the hull better. I suspect that a simple curve will serve perfectly well.

I completely agree that adding rocker to the extension is wrong. In fact a slight reverse of the rocker curve should benefit the PDQ36 by reversing the suction of water at the stern. The 32 benefitted from lessons learned from the 36, and carries the added weight of a dinghy very well. The boat is perfectly delightful except that its length overall fits unfortunately well in the waves on most of the Chesapeake, leading to a bit of pitching.

I have some reservations about a bolt-on extension because of the excessive loads encountered in a middling collision with a piling, seawall, or acrobatic whale.
Glassing an extension just as Pacifica did is much stronger, easily reversible and ensures an invisible transition from boat to faux fat fannies!
Sandy Daugherty "Page 83" PDQ 36026
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Re: Transom extention vs. swim platform

Post by thinwater »

The seat idea is interesting. I'll have to think on the geometry. Certainly a good phase II for when things become more difficult.
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Re: Transom extention vs. swim platform

Post by thinwater »

Moral support needed!

I elected to extend the transoms and today we started cutting. It's always a little troubling to tear into all that beautiful gel coat, not certain if you can put it back together better than you found it.

Today's tasks:

* Bottom prepped for paint; it was pulled for that anyway, as it has been 2 years.
* Molding pulled up and out of the way. Attached with polyurethane, so some prying, pulling, cutting and groaning were involved.
* Ground 12:1 bevel on inside of flange. Will do same on outside after mold is pulled.
* Sheet metal mold installed with ropes tensioned to winches and screws into the flange. Seems to line up nicely.
* About 5 layers of glass cloth and triax. Lots more needed but hands started cramping from a day in the heat.

A long day in the heat. I'll post something on the blog when finished. So far I like what I see. The extension will be about 18 inches and will leave the transom about 3-4 inches above the water at rest when lightly burdened. A longer extension would simply leave the transom ridiculously high and have too many potential down sides; this should be enough to improve boarding and clean up the wake.
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Re: Transom extention vs. swim platform

Post by Page 83 »

That first step is a long one! Congratulations. Don't stop before the last steps. Show pictures!
Sandy Daugherty "Page 83" PDQ 36026
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Re: Transom extention vs. swim platform

Post by thinwater »

Check my blog. A long post there!
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