subaruguru

Hi Ed, (et al?)

Yeah, 1/2 WL is out of the question, and as I remember just doable for 2m portable ham, but I was too young to drive back then!

Couldn't remember the efficiency diff between 1/4 and 1/2WL monopoles, but a google popped up the following, suggesting best performance of a coil-based monopole of a way too longish 5/8WL:

http://www.smeter.net/antennas/bottom-loading.php

Another site referred to bent monopoles, like a "meander antenna" that I suppose are more compact, but I'm still intrigued by the possibility of adding a 1/4 WL to our marine VHF to see if transmitting "reach" is dramatically improved.

Are our SH and iComm units 1w max or really pushing 5w? That would be damned-quick battery drain....

G'night, and thanks for the trip down memory lane.

The short antennas supplied on handheld radios of all types are known as a rubber ducky and jokingly referred to as a dummy load by hams because they are not efficient by any means.

However, it is not simply a short antenna in terms of its electrical as opposed to physical length as this article shows.

http://en.wikipedia.org/wiki/Rubber_ducky_antenna

All things considered they are a better antenna, by far, for the intended use than a physical 1/4 or 1/2 WL vertical attached to a handheld.

Been there, done that. Not going back.

It is true a rubber ducky is about 6db down from a good 1/2 WL antenna which in turn means for the same field strength it needs to be driven with four times as much power which in turns means more current and faster discharge of the battery. However a 1/2 WL (physical and electrical) antenna for marine VHF use is way too big to be practical for a handheld used by a kayaker.

Ed Lawson

I know, I know. It's just a whatever-length aided by a tuned coil. I used to have to build them to trim long ham antennas as a kid too. Basically a box of coils and switches so that one could use a fixed-length antenna for different wavelengths, "tuning" its electrical length easily. Beats getting on a ladder in the winter or in a storm!

I just noticed that the Standard Horizon I have has an exposed 7" flex-whip...probably extended 2-3 inches into the body, totaling about 9.5", or a 1/8 WL. Is it then "goosed" with a coil or some other means? Dunno.

To cut to the chase: I simply wonder if using a true 1/4 WV (19") would significantly improve reach, and therefore reduce battery usage too?

I could imagine some kind of waterproof "extender" that could pull out and extend the existing 7" to 16" (+ 2.5" in the base)? Or an upside-down "J" that could loop GENTLY around one's neck? Ok ok....

I'm discussing this very topic with the clowns on an auto site who are comparing cute stubby antennae. I just killed an hour comparing sensitivity vs antenna length using FM (88-108...not too far from our 146MHz) and an efficient and reproducible capture ratio used by the seek function of an auto receiver. Worked nicely:

Antenna Length (in) ..... Stations "captured" cleanly

0" ... 3 stations

1" ... 13 (anything's better than nothing!)

2" ... 13

3" ... 14

5.5" ... 21 (starting to get somewhere)

8" (1/16 WL)... 24

16" (1/8 WL).... 29 (nice compromise for a fixed car antenna)

24" ... 34 (this increase was a bit unexpected)

31.5" (1/4 WL) ... 37 (nice old-school telescoping whip for an auto)

41" (whip max) ... 37 (as expected, no improvement over 1/4WL yet)

63" (1/2 WL) ... wish I had one on hand....

You said "Been there. Done that." You've tried an 19" 1/4WL antenna on a marine VHF? What'd you find? I understand the not insignificant ergonomic hurdles, but I'm very curious about performance improvement.

Ern:

I have some thoughts on antenna length, but before saying more would like to know what you mean by this. Are you saying that if they used a more efficient antenna the radios could be designed for lower wattage output only which in turn would mean a smaller battery or at least enable the existing batteries to last longer?

Ed Lawson

Hi Ed,

That's my hypothesis. An antenna is really a transducer of sorts. Or maybe think of pushing a fluid through a pipe: the smaller the orifice the higher the pressure needed to move a given amount.

When I was a kid I learned that it wasn't so much the power of my ham radio transmitter that was important as it was using as long an antenna as possible that was tweaked to match band wavelength (in this case I recall c. 80 ft being correct for high efficiency, as I didn't have a 160 ft yard).

Hi Bob,

Interesting premise re battery management, but I believe that ergonomics (VERY short antenna) is a given primary design constraint, and that the balancing act becomes battery type (cost) vs. power output, and thus drain cycles.

However I think the "overdrive" issue you mention is a red herring for portable marine VHF, as saturation (signal overload) and possible resultant audio clipping is not a critical issue. As kayakers don't we struggle more with antenna placement (keeping it as high off the water as possible to help with earth's curvature) while using an incredibly inefficient antenna both for reception AND especially transmitting? I don't think intelligibility is compromised by overload as often as by poor signal to noise ratio, and the latter can be greatly improved with a longer antenna.

Because reception requires little power, battery issues are less critical, but in transmitting we're really trying to push a signal through a small hole, using as much power as possible for only meager success. It occurs to me that a limiting factor too is overheating via too-fast battery drainage. A friend of mine flies RC gliders using tiny super-high RPM motors that drain a battery pack in in 90sec, getting both REALLY hot. Can't have that in a small radio either....

Again my antenna thoughts are based on classic RF theory and NOT state of the art product designs. Hence my post-hibernation queries....

Nice to hear from ya.

Received the latest West Marine mailer touting all the new radios while reading an email from a fellow paddler annoyed that his new fancy GPScumRadio's antenna tickles his left nostril. Well!

I just finished replacing my 1/8 wavelength Miata's FM shorty antenna (16") with a "proper" old-school 1/4 wave (31.5" for NPR/college c. 90MHz), and will be comparing S/N ratios (probably cheating by just using the autoscan counts).

So naturally my brain cross-fired and I thought about calculating ideal antenna lengths for our VHF use (156-177 MHz). Simply:

1/2 wavelength: 72" (some say 5/8 wave can be better: 81"!)

1/4 wavelength: 36" (damned good)

1/8 wavelength: 18" (pretty ideal compromise for kayaks?)

1/16: 9" (yech...getting pretty weak, but has that old-school look!)

1/32 wave" 4.5" (probably what's used in the bulk of our modern choices...and pretty useless without unobtanium batteries?)

Manufacturers have to use HUGE battery power and thus fast drain-rates to overcome the poor signal strength capability of such short antennae.

Anybody successfully install a waterproof true 1/8" wave (18") telescoping antenna on their portable marine radio? Could be good for poking, pointing out seascape features, etc....

Or what about a flexible J-shaped 18" "hook" antenna that could, oh I dunno, hang around one's neck, solving both the attachment AND signal strength issues simultaneously?

Thoughts? Ideas? Pros and cons?

Huh, where's this greater driving force coming from? You’re probably thinking about momentum which isn’t a force on the boat. The heavier boat goes slower because:

1. The extra weight sinks the boat more (the draft increases).

2. The increased draft increases the boats surface area.

3. The increase surface area increases the frictional drag.

In addition there is an increase in wave drag (see below)

Neither John Huth nor Leon can suspend the laws of physics. A significant component of wave resistance comes from the fact that water must be pushed apart and then drawn back in to fill the hole left by the passing kayak. The heavier the kayak the higher the total displacement which means that more water must be pushed apart. Thus, everything else being equal, the greater the total displacement the greater the power required to move a kayak at the same speed.

Leon,

I know you are the club racing guru. I don't think I'm disputing the laws of physics in my explanation nor do I dispute your take on this but there are other factors that compensate for the increased draft not effecting speed. Please specify how my take on it below is incorrect. I really want to understand this.

An 18 foot racing boat with 17' of waterline that displaces more water vs. an 18 foot sea kayak with a 15.5 foot waterline that displaces less water. The racing boat that displaces more water is faster. I think there is more to it than your theory depicts. I don't think the displacement is nearly as important as the hull design and how it displaces the friction or drag. You can displace more water and still have a faster boat. A sea kayak for example that has more rocker compensates for this displacement of water when adding weight. By adding weight you are compensated structurally by a lengthened waterline, a deepend V-line and decreased rocker thus reducing friction and not reducing speed.... I believe.

Doug

Oy oy oy!

Respectfully,

Archimedes

I bought(received for Xmas) a 70P compass for installation on my p&h which has a place moulded into the foredeck specifically for the unit. When I looked at the boat and the position of the compass indentation it occurred to me that with my 65 yr old eyes and bifocals it may end up being a simple ornament and added weight.LOL Thank God for the hand held GPS with a compass function!

I was going to offer a rec for the Brunton 85R flush-mount, as its larger card is MUCH easier to read than the ubiquitous 70, but since you had a built-in recess....

But now that you're complaining... think about mounting an 85R a bit closer. It's a great compass, and I strongly prefer it to its smaller cousin.

Sometimes a bit cheaper, too, is you can find one.

Hey Fellow Paddlers.

Finally decided to clean out all 2000-2004 Subaru Legacy/Outback and earlier Impreza parts and accessories I gathered and traded over the years.

Of most interest are 3 sets (6) of Yakima-designed Subaru OE "aero" roof rack crossbars for those members who want an extra or need one to replace a bent one, etc.

Will gladly trade for a rolling lesson or a handful of Blanxart bars if you're visiting The Continent this winter.

Also have a foglight, taillight, and a bunch of rear tonneaux (cargo covers) if you want to hide your stuff.

MANY extra OE (Panasonic/Clarion) Radio/CD/Tape single and double-DIN audio head units in case your CD transport (or cassette!) is on the fritz. Fit 2000-2004 Leg/OB, 1993-2011 Imp, and some Foresters.

Lastly, a pile of sundry sensors, connectors, bulbs, again for previous gen Subies.

Note that this stuff will NOT fit the 2005-2009 Leg/OB gen, my current metier.

Keep warm and safe!

Ern

TSG

781 483-3922

In the merriment of raffling 45 gifts to our lucky Holiday Party attendees I forgot to offer the only joke I thought up for the event:

"A fellow paddler, having grown up with vague memories of blessings of fleets, decided to cover several bases after purchasing a new kayak.

He watched as a priest sprinkled water on it, and then held hands with a minister as they prayed, but was chagrined after the shaman finished chanting when the rabbi ran over to his beloved newbie, flipped it over and cut off a half-inch of its skeg!"

Sssss....BOOM!

This means I'll probably initiate a bunch of mid-week harbor paddles next season.

Yippee!

Hey Bob,

I should be able to attend and help out, as before.

Glad we could resuscitate this CWW.

Thanks,

Ern

Amazing...breathtaking. Thanks for posting!

Ern

Hi Ben,

I forget where I bought the bright red stuff that's been holding up for over three years now on my carbon paddles, but while at a True Value yesterday noticed that 3M is producing their Duct Tape in orange, red, bright yellow, et al, for cheap. May be worth a try.

Ern

Mike,

Terrific!

See you at 11. Best to park in the rear near the trees.

Ern

Tom H and I are meeting up tomorrow (Sunday) at 11AM at Tuck's Point, Manchester, for a leisurely L3. Winds will be light SE, so we'll probably head up towards Gloucester Harbor to maybe catch a lil' push back.

Actual agenda to be decided by participants at the briefing. Promises to be a great day!

Ern

Surprised to find no word here from she who is known as The Swearing Ferret...but there we are: perhaps she is not around.

Sorry to see that Phil and Ernie will not be making it -- Beckers, you want to go paddling tonight?

Tom H and I will set out of Tuck's Point at 11:30 Sunday if you want to join us. I'll double-post.

Ern

Oh boy....sorry if this fizzles, Godfrey.

Tom H and I are hoping to get out on the water Sunday (tomotrrow). Wanna help plan something?

Anything from easy Tuck's/Lane's choices or a deer launch to the Hahba Islands works.

Ern

Greetings!

I may be up for either day or eve, but cannot commit yet.

Keep me in the loop.

Ern

Later: too late.

Gotta work Sat PM.

Next time.

Lis,

Just a quickie: I had a fitness Kayakpro JET with a OE "pull bar" attached ahead of its footrest plank. I assume this setup is prevalent for these types of kayaks?

See ya in the sunlight.

Ern

Join Leon, me et al at Tuck's Point Manchester at 11AM Tuesday for the pick 'o the week L3-4 paddle (agenda to be decided at briefing).

PM for easy parking.

Ern

Does anyone have a small kayak that I could borrow for a 5 year old child who is 45 lbs and 45 inches tall ?

Thanks,

Karen

Hi Karen,

I have a Necky RIP (8 foot surfer) you can borrow anytime. I can't comment on the appropriateness of its use for a child, though. Call me at 781 483-3922.

Cheers.

Ern

And test your straps.

I was amazed the other day when the Malone strap, which I had been using for a few months to secure a tarp over my boat, basically crumbled in my hands. Sure, it was faded red from sun exposure, but the way it broke in two from a light tug was a shock.

.......My new RED MALONE STRAPS failed within a few months of exposure too. Clearly a defective batch.

Ern

Sounds terrific. I'm a most probable attendant!

Ern

Ern,

If you reread your text:

It sure seems that you did have the two confused in your text. The Qwest was out in 2000 or before. The Q Boat was released in 2005. Any way, I would suggest that you spend a few days in a quest before deciding it's not stable.

-Jason

No confusion re the two hulls, only the Qwest's date of introduction: CRCK had described it as a "new" boat (maybe just to their fleet?) on the paddle in 2005 or 2006. I'd assumed new MODEL too. My small error.

Also, please read more carefully...I'm just quoting OTHERS" descriptions of stability profile, and what I SAW when one spilled a newbie twice and a proficient paddler once; and of course the repeated CRCK concise description from just last Friday, which would indicate that it may be a great match for someone of your size, strength and rolling skill, but perhaps not a smaller, older guy of less experience as our newcomer. But maybe his son is a better fit, and with advancing skills will fit it fine. I suspect they'll find out in time, as we all do.

The Quest is an old Derek Hutchinson designed boat make by P&H it has been around since at least 2000 and is a very very different boat from the Valley Q Boat.

I know. I didn't confuse the two "Qs". The Q-boat (was it called the Qariaq?) story was to illustrate that even the most experienced paddler (Keith) admitted that paddling a hull that's NEW to him can lead to difficulties in unexpected conditions.

Doug's reference to that incident tweaked my memory:

A few weeks following I met Keith as we were co-safety-spotters at an REI Demo Day. Not having any knowledge of him nor the USCG-involved event, I asked him what happened. Long story short (see that post) he summarized that a good deal of the problem was his unfamiliarity with that newer kayak (Q boat) in those conditions, adding that he thought he would've been ok, and NOT capsized, in his tried 'n true Explorer. VERY interesting....

The Quest premiered right around the time ('05?) I took a first Ocean Skills Session with CRCK in Cohasset. They used the new Quest for a larger guy, who quickly capsized twice in only very light chop. The assistant staff trainer promptly swapped 'yaks with the paid participant, but also capsized in moderate chop later (it was an unuasually choppy day...estimated by Dave (CRCK) at 4-5 footers at one point!).

Once we hit the current/eddy work, there's was an all-in, as expected, with further training, and all went well.

Not having heard much about the Quest since, I asked about it again, and was told that it's a 'yak for "a really big guy with good rolling skills who can control its combination of high volume cockpit and tender hull."

So maybe incorporate that bit of reference in your thinking and kayaking plans.

Maybe the Quest is better for your taller and heavier son, assuming he doesn't mind a rounded hull, and can advance to control it in conditions?

The cowboy entry is still not within my repertoire, even in a pool! So although it sounds like you're a natural athlete, strong swimmer, etc., I would exercise the caution all have suggested, as well knowing that your paddling an advanced hull that may be more easily tamed by a bigger guy, or maybe added ballast? I dunno.

Good luck, and be safe. It can take awhile to learn all the handling quirks of a new hull in "conditions", as both stories indicate.