JohnHuth

Waves typically consist of little parcels of water going in a circular orbit. When water gets shallow, the orbits become more elliptical. The bottom creates drag and, as it gets shallower, the wave velocity decreases. This makes the waves get steeper. At a certain point, the ellipitical orbits are broken and the waves then break. When the waves get steeper, they tend to break, and this creates chaotic motion, which dissapates (via friction) the energy of the waves. There are different shore conditions, and these create different drains on the wave energy, based on the amount of drag from the bottom: 1.) A shallow run-up to the beach creates a slow dissapation of the wave energy over some distance. 2.) A very steep run-up to a shore will create dumping waves, which will loose most of the energy right at the point of breaking (e.g. Butler Hole on Monomoy is a good example of this). 3.) A large cliff (e.g Schoodic Head, up in Mt. Desert) will just reflect the wave energy back out to sea, creating a difficult situation with incoming waves colliding with outgoing waves. (i.e. little or now dissapation of energy)

A few general comments - the spectrum of wave heights will vary a lot, depending on a number of factors. For example, ocean swells that are fully developed, in the open ocean and away from currents will have a much more regular distribution - you won't get the large outlyers in that example. The waves are all sinusoids and more constant. On the other hand, currents can focus waves and you can get a much higher chance of a large "freak" wave. Another exception is when you have multiple sources of waves - e.g. a swell coming in, adding to a wind-driven set of waves. This can also generate a higher chance of larger waves. Finally - the rule of thumb for when waves start to lose their power as the water shallows up is that if the depth is less than about 1.5 times the wavelength, then you're in the "shallow-water" condition and waves start to peak and lose power.

I'm trying to assemble something a bit more comprehensive for my repair kit than a bunch of duct tape wrapped around a Naglene bottle. Does anyone have suggestions for a reasonable repair kit to take on a multi-day outing? Thanks in advance, John

Congratulations!! There is this very frustrating "just about there...but only if...." time (usually coinciding with the advice about lifting the head too early). (I also like the Crash Davis' line "Don't think, it can only hurt the team" - this is my mantra). John

Legislation based on a single incident is not a good idea. If there's are repetitive incidents, then that's another matter. FWIW....I know Tom Leach. He's well meaning - I won't try to defend his legislation. Here's a story - I was kayaking last summer in Nantucket Sound. A dense fog rolled in, and I was paddling by compass. As I approached some rock groins, I found out that two boys were lost in the fog. The police, coast guard, and harbormaster were all called out. I had a portable fog horn, and blasted it a bunch of times. One of the boys heard the sound and followed it to the shore. When I told Tom this, he came up with an idea for the classic "lost in the fog" report he has to respond to - bring a bunch of cars right up onto the beach, and start honking the horns. Here's an idea which isn't legislation, but is a "best practice" for search-and-rescue folks. The "lost in the fog" scenario happens very regularly on the Cape. I daresay that it'll happen three or four times this summer on my little stretch of the Cape alone this summer.

Right - I was thinking about the front (seaward portion) of the bar, when they first start to hump up. It was a simple calculation - not a thorough analysis.

OK, thanks. I did a little calculation. If the 8 ft. wave report was in "deep" water, in "shallow" water (say, 10 ft. depth), the height would be more like 12 ft. (that's because the wave velocity slows down in shallow water and wave heights increase accordingly). If this is coupled with an outgoing current, you'd end up with very tall, very steep waves. I'm also wondering whether the location played a role - with NNE winds and a pretty long fetch, there may have been a lot of cross-wash with swells from the Atlantic banging into the wind-driven waves. Put it all together, and it sounds like very very difficult conditions. (in hindsight, mind you!...)

Just out of curiosity - do you know what the long distance swell from the Atlantic was during that time? You had NNE winds at 15 and an outgoing current - right?

Once you assemble the information - it might be useful for someone to construct a small current chart. I started to do this for the currents around Nantucket Island - for at least three or four hours after high tide - I still have to complete this. A big eddy and strong rips, huh? Sounds like it would be confusing and difficult.

I know that there's an outfit that goes out of Seal Harbor, although I forget the name, off the top of my head. A very nice paddle is from Seal Harbor over to Little Cranberry island. I've seen a number of organized groups do that. As someone mentioned - the water is very cold up there. Dress accordingly. By the way, if you do paddle out of Seal Harbor, you'll see a monstrosity of a house. That's owned by Martha Stewart- it's right at the western entrance to the Harbor.

I was at the Hopkinton Resevoir last weekend, and it was quite warm. I wore a wetsuit, but could've easily gotten away with swim trunks and a light polypro top (and I was in the water a lot - practicing reentry-and-rolls, among other things). (I also tend to be pretty warm-blooded, however) Hopkington is pretty shallow.

>...which is why they are ideally sited either offshore of >the Kerry or Kennedy compounds. > I *knew* there was some logic to the sites. Thanks, Bob.

No great wisdom - but I certainly thought of the cynical answer - the Nantucket Sound version can be seen from the Kennedy compound in Hyannis. Having said that - the local Cape Codders love the idea of the wind farm. I can't tell whether it's the old spirit of Yankee independence or because the rich folks don't like it. Maybe it's both. I did talk to a friend who knows a bit about alternative energy and she said that the environmental impact of these things can be pretty severe - they make a lot of noise and that tends to drive away the fish. Anyway, this is all hearsay and opinion. Take it with a grain of salt.

I'm glad I'm not the only one who has problems putting a spray skirt on underwater - I thought this was a unique clumsiness on my part.

I'm quite comfortable in the 170, and I'm not that large. Maybe I'm doing something wrong? The leg placement makes me feel like I have a lot of leverage - as I can bring force for pitch/yaw/roll efficiently.

Temperatures are a bit warmer now than these averages. Example: Boston Harbor is around 41 degrees F - not out of drysuit territory by any stretch of the imagination, mind you.

I have a fiberglass Tempest 170 - it's great! My only minor nudge is that the hatch covers tend to leak - there are various purported cures for this. This only really shows up in heavy seas, with lots of wash over the deck. It's never been so serious that I've had to resort to RTV to cure it, so it's manageable. Overall - great tracking, good at carving turns, surfs well, easy to roll. I'm 5'10" - am XXX pounds, but look much lighter. John Huth

Hmm.... I wonder what Adam Bolonsky would use for a lure for this one? A half-size gray seal imitator? It might be interesting to land.

I tried to poke around for any statistics I could find. I'm guessing that the situation of "stay with a large boat" versus "paddle to shore" hasn't had any documented successes or failures, so it's a bit speculative. I'd head for shore, not knowing anything about the vessel I was next to, despite the USCG advice. I found a few freak examples - people in Outward Bound on Hurricane Island who got zapped on the beach from a bolt that struck a nearby tree and the current traveled through the roots. The main problem with thunderstorms is wind. When I see a squall front bearing down on me, my first thought was to worry about the wind, and I didn't give a thought to lightning. The question is primarily academic, given the lack of data, but having seen some freaky lightning, I'd stay away from the boat with the tall mast. My scariest experiences were in the woods - with neighboring trees that got hit repeatedly. The other data point is on Electric Pass - up in the Rockies. It is total folly to be on this pass in the afternoon in the summer. Your hair stands on end, and you hear a buzzing sound. Many people climbing over this pass experience this - very dangerous!

I'm starting to run out of practical experience, here - I can only speak to the physics and now enter the realm of my opinion. There are probably statistics compiled about this kind of thing. My concerns with an aluminum mast with a groundstrap to an electrode in the hull would be two-fold: First: transient (very fast) currents can take erratic paths, and might jump from the mast, directly to something else, depending on the "inductance" (tendency to resist fast current changes) of the path through the hull, Second: I'd worry about the reliability of the connection - the electrodes are subjected to a lot of oxidation and could lose conntection to the mast over time. On the other hand, a pointy, lightning rod structure might provide a continuous discharge and relieve the charge build up before it became an issue of a strike. Even armed with the knowlege that most boats with aluminum masts have a ground strap, I wouldn't seek them out in a thunderstorm as safe against lightning. In part this is my own internal risk-evaluation. The odds of something going wrong is small, but the consequences are huge.

It's certainly true that, given some time, you could design a system like this. If I had to, from scratch, I'd probably use a mast with a lightening rod, and perhaps some barbs on it, and then have a good groundstrap (like what welders use) and then run it to some electrodes on the bottom of the hull. That would probably cause a sufficient charge dissapation from the sea and boat to the atmosphere to reduce the chances of a strike substantially. This is, in principle, what happens with St. Elmo's fire. The problem, as I see it, is that any random large boat will be a larger target for a lightning bolt unless it has something to dissapate the charge, like a system like this. So, if you knew a vessel had a system like this, it would likely be safer, but if you had no idea, the vessel, in all likelihood wouldn't, and then you'd be more likely to get hit from an arc skipping off the mast.

Some more thoughts: Lightning occurs because the clouds acquire a large positive charge on top, and negative charge on the bottom. The convection/condensation of large updrafts feeds this. On the ground, positive charges are attracted to the negative charges on the cloud bottom. The charges tend to congregate most on "pointy" structures. The potential difference between the ground and a cloud can get past 1 million volts, and depending on the geography and other factors, the charge concentration can get to be high enough to make electric fields that will ionize air. Once you get into this situation, the chances of a breakdown, making a charge channel out of ionized air is very high, and pretty unstable. For someone making apparatus that runs at high voltages, this can be particularly annoying, as it's difficult to eliminate little points that will periodically arc over. The lightning rod will work for continual discharge. St. Elmo's fire is a variation where the pointiness of the masts of sailing vessels would make a continual discharge into the air, neutralizing the charge. Here, a low current that feeds from the ocean into the masts and into the air provides a slow release of charge. In other cases, the charge may build up until the field gets very high, and then, suddenly, the charge channel will open up, and a very high current bolt of lightning will occur. In this latter case, the actual conduction channels are much more dicey. They can arc over all sorts of structures, and take funny paths. In the case of a sailing vessel or boat with outriggers, I wouldn't count on a lightning rod effect, although I suppose you could outfit them with lightning rods. The ends of the masts are usually rounded and have some kind of pulley on them for the sails, so I don't think these would act like lightning rods, and would tend to be more of the variety that would build up charge and then have a large bolt, in which case, there are no guarantees about the conduction path to the water. In the case of a shallow cave, you're getting an arc down the face of a cliff, and it frequently arcs over the faces of shallow caves. I hope this helps.

As luck would have it, there's an internet connection here. But, the surf's calling and I can't go through all of this. A few physics points: 1.) The lightning rod is a design by Ben Franklin. "pointy" structures tend to have large charge concentrations and large electric fields. When the field gets high enough, the air begins to become ionized - this immediately opens up a conduction path - much like a wire. Tall trees and structures often are hit because they offer up the largest, isolated, collection of charge and hence are the first place to see breakdowns of the air when there's a large buildup of charge. Franklin invented the lightning rod as a very pointy metallic object to put on the top of steeples, etc. The idea is that the "pointiness" is so sharp that there is huge electric field, making a nearly a continual discharge, and it doesn't allow the charge build-up in a normal steeple. Without it, one would tend to get a very large charge build-up, then an instability, then a bolt. The lightning rod provides, in a sense, a continual electrical discharge - a lot of very tiny lightning bolts, rather than one massive one. 2.) Unless a boat is equipped with a real lightning rod, it's subject to the possibility of a large charge build-up. If you're near a boat that gets a discharge, it's anyone's quess what the path would be, but I think it would scare the daylights out of me, even if I wasn't in a conduction path. I'd stay away. 3.) Shallow caves or shallow overhangs: avoid them - frequently the path to ground will arc over the top of a cave and will find a conduction path through the cave or overhang. 4.) Someone pointed out the random nature of strikes - this is true, up to a point. There are structures that tend to collect charge, and it's not always easy to see the conduction paths - depending on how much seawater might be sloshing onto a buoy, or how wet a surface one might have. More when I get back

I'm open to any suggestions. Part of my problem is that I have a high metabolism rate. I have a Goretex Kokatat (sp?) and the gaskets aren't so bad - maybe it's the layer of polartek underneath I put on. I try the immersion test, and I find that a layer of polartek works well, but if I paddle on a hot day in April, I sweat a lot. I don't know of a way to ensure you'll stay warm in the water in April, and not sweat a bunch on a warm day in the air.

For drysuits. The air temp warms up, but the water temp is still waaay down there. You end up sweating like a pig in the drysuit, but what choice do you have? Bring lots of water!