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glythcott
06-19-2009, 11:20 PM
The race instructions require a non-octahedral reflector to have at least a 10 meters squared radar cross section. The 2" dia Mobri reflectors only have 2 meters squared cross section and the 4" dia ones a 4 meter squared cross section. How many of these things am I required to carry...2 of the 4"ers and one 2"er? It seem like a lot to have aloft. I hope I'm just not understanding.

George/TAZ!!

AlanH
06-20-2009, 02:00 AM
The race instructions require a non-octahedral reflector to have at least a 10 meters squared radar cross section. The 2" dia Mobri reflectors only have 2 meters squared cross section and the 4" dia ones a 4 meter squared cross section. How many of these things am I required to carry...2 of the 4"ers and one 2"er? It seem like a lot to have aloft. I hope I'm just not understanding.

George/TAZ!!

While I had two Mobri knockoffs aloft in the 2008 TransPac, I only had them up there because I already owned them, and they didn't do me any good sitting in the berth. However, several independent tests basically tell us that the Mobri type reflectors are pretty awful. For one thing, their response drops off drastically when the things are at anything more than 5 degrees of heel?

You think you might be heeled more than 5 degrees, much of the time?

Just go by a big Davis Echomaster and string it up. It works. You can also buy a Luneberg reflector, but they cost a mint and weigth a ton. Go look at West Marine's prices on the Tri-lens..

Some radar reflector reports:

http://www.ybw.com/auto/newsdesk/20070409144703pbogeneral.html

This is old, now but well worth reading, especially as Stan Honey was pretty closely involved. The Mobri is in there.

http://www.ussailing.org/safety/Studies/radar_reflector_test.htm#INDEX

Here's the text of the rule from the LongPac Rules:

Radar reflector properly mounted at least 13 feet above the water. If a radar
reflector is octahedral it shall have a minimum diagonal measurement of 12 inches.
If the reflector is not octahedral it shall have a documented radar cross section
[RCS] of not less than 10 meter squared.

So you can have an octohedral radar reflector, as long as the diagonal measurement is 12 inches or greater.

http://www.davisnet.com/marine/products/mar_product_docs.asp?pnum=00153

Go to that URL, and grab the pdf for the instructional manual for the new Davis Echomaster. This is an octohedral radar reflector. It has 12.5 inch circular plates, and it satisfies the rules requirement for 50-something bucks

Here are West Marine's prices on the Tri-lens radar reflectors, which are not octohedral reflectors.

http://www.westmarine.com/webapp/wcs/stores/servlet/producte/10001/-1/10001/64227/377%20710/0/trilens%20radart/Primary%20Search/mode%20matchallpartial/0/0?N=377%20710&Ne=0&Ntt=trilens%20radart&Ntk=Primary%20Search&Ntx=mode%20matchallpartial&Nao=0&Ns=0&keyword=trilens%20radart&isLTokenURL=true&storeNum=8&subdeptNum=52&classNum=275


Now look here for information on the Tri-Lens

http://www.tri-lens.com/trilensweb12002002.htm

There's a mini, a regular size and the large size. The only one of the three that has the equivalen tof 10 m squares area is the large size, and it costs $839 at West Marine and it weighs 12 pounds. Ouch.

The Echomax EM230+

http://www.landfallnavigation.com/sem230.html

and West Marine's prices...

http://www.westmarine.com/webapp/wcs/stores/servlet/producte/10001/-1/10001/81639/377%20710/0/echomax/Primary%20Search/mode%20matchallpartial/0/0?N=377%20710&Ne=0&Ntt=echomax&Ntk=Primary%20Search&Ntx=mode%20matchallpartial&Nao=0&Ns=0&keyword=echomax&isLTokenURL=true&storeNum=8&subdeptNum=52&classNum=275

Actually has a greater-than 10meter squared profile, though hits 10m squared at 30 degrees of heel, but look at the price!

The answer to this is to just go buy a Davis Echomaster and get it up in the rigging 13 feet off the water for your inspection. Note that the reflector does not have to be PERMANENTLY mounted, just "properly" mounted. You can haul it up on a flag halyard, or a line slung off your backstay.

AlanH
06-20-2009, 02:26 AM
Having said the above, if anybody wants to hang an echomax EM230+ 13 feet up their mast, I will certainly pass it. Ditto for the large size tri-lens.

glythcott
07-03-2009, 01:10 PM
Thanks for the advice Alan.

I went with the Davis Echomaster. I've installed a pennant halyard and the reflector will be just below my lower spreader.

George

Alchera
07-03-2009, 01:28 PM
Thanks for the advice Alan.

I went with the Davis Echomaster. I've installed a pennant halyard and the reflector will be just below my lower spreader.

George

If you want to keep it from flopping around, tie two short loops of cord one on each side. One loop goes around the nearest shroud, the other around the pennent halyard. When you raise it to the top it will be supported at four points.

- Mark

BobJ
07-03-2009, 01:36 PM
If you want to keep it from flopping around, tie two short loops of cord one on each side. One loop goes around the nearest shroud, the other around the pennent halyard. When you raise it to the top it will be supported at four points.- Mark

I mount mine a little loose so the main won't grind on it as much (when running). Also, those stamped-out edges are sharp - sand around all the edges and apply a couple layers of rigging tape to them (white electrical tape works best). Beats slicing up your main.

blighbaum
07-03-2009, 04:14 PM
Last year before the SHTP, I e-mailed the Davis company and asked whether putting electrical tape around the edges of the echomaster would impair its effectiveness; they replied that it would! Based on that, I sanded down the sharp edges and left off the electrical tape. Some ships said they could see me on radar, and I still have my mainsail, so I guess that worked. - Tom Kirschbaum, Feral

Alchera
07-03-2009, 05:40 PM
Last year before the SHTP, I e-mailed the Davis company and asked whether putting electrical tape around the edges of the echomaster would impair its effectiveness; they replied that it would!

I find that very hard to believe. Sounds like you may have gotten a response from the company lawyer rather than a techie. From what I understand, plastic is pretty invisible to the radar spectrum, that's why it's ok to mount radar units behind plastic. Anyway, I've had plastic tape on my Davis edges for years and ships have seen me just fine.

- Mark

blighbaum
07-03-2009, 09:04 PM
Well, that's what they told me. Maybe they realized that I am a lawyer, and, as you suggest, gave me the legal department. But would one lawyer give another lawyer bad information? Is there no honor among thieves? Perhaps my e-mail to them asked specifically about duct tape, if that would make any difference. Maybe the reason my echomaster worked better on the SHTP than on the Longpac is that I had it tied laterally with a loop to the shroud on the SHTP but not on the Longpac.

Anyway, have a great Fourth!

- Tom Kirschbaum, Feral

Alchera
07-04-2009, 12:56 AM
Perhaps my e-mail to them asked specifically about duct tape, if that would make any difference.

I don't know about duct tape, I think the standard brand duct tape made from vinyl and fabric would be perfectly OK. But the metal foil tape which is actually used for sealing heating ducts would not be good, since that would affect the radar signal. Maybe that's what they thought you were referring to, which might explain their response.

- Mark

BobJ
07-04-2009, 11:23 AM
Keeping the Davis reflector in hanging basket ("catch rain") orientation is the most important factor. A bit of slack in its halyard should help as the boat heels. Davis also recommends it be 10" below the spreader, with a loose loop around the shrouds to keep it from spinning. Our rules require it be 13' above the water - this might be close on smaller boats with upper and lower spreaders.

As to the tape, I use plastic electrical tape. I think it's thin enough around the edge for the taped-up reflector to still be in compliance with the diameter requirements (per Alan's post above). Besides, given the choice of a possibly weaker signal or damage to my primary means of propulsion (my main), I'll accept the weaker signal.

Thom
07-04-2009, 02:56 PM
Sure you can stick some clunky mainsail cutting octagon device up your mast...but you can also just put up what is essentially a whip antennae (another one) which is a radar target enhancer. It retransmits the radar sweep it receives at a cost of 350 mA. Only works in X band and some ships still have radar in S band...but still, you will get seen better by most. Sea-Me?:p

http://www.theradarreflectorsite.org/

BobJ
07-04-2009, 03:34 PM
Ruh, roh . . . can a Mini discussion be far behind?

The Sea-Me has been floated out here before. It's less than a pound (plus mast-length power cable) but is supposed to be at the masthead. One of the math gurus (like Thom!) can tell us how that compares with the Davis Echomaster at the lower spreader.

But the main thing is the Sea-Me's $750 cost (at today's exchange rate). I paid $35 for my Echomaster and have had it eight years.

haulback
07-05-2009, 06:19 AM
Another place to mount radar reflector is to permanently lash it on to the backstay.

I put mine there and it looks to be sitting on a more-or-less 'catch rain' position, beats the regulation 13 feet above LWL and far out of the way of having any chafe issues with the main.

Jim/Haulback

tiger beetle
07-06-2009, 03:55 PM
Ruh, roh . . . can a Mini discussion be far behind?

The Sea-Me has been floated out here before. It's less than a pound (plus mast-length power cable) but is supposed to be at the masthead. One of the math gurus (like Thom!) can tell us how that compares with the Davis Echomaster at the lower spreader.

But the main thing is the Sea-Me's $750 cost (at today's exchange rate). I paid $35 for my Echomaster and have had it eight years.

The key feature disqualifying the Sea-Me from the LongPac RRC is that Sea-Me is a powered unit, and of zero value if the boat has no electrics. While it appears to be a good unit on X-band, the RRC requires the yacht have a passive radar reflector.

- rob

jfoster
07-06-2009, 08:03 PM
The key feature disqualifying the Sea-Me from the LongPac RRC is that Sea-Me is a powered unit, and of zero value if the boat has no electrics. While it appears to be a good unit on X-band, the RRC requires the yacht have a passive radar reflector.

- rob

If you are looking for an active radar reflector, anyway, ( you could have both types on board) the state of the art seems to be the Echomax Active X Band (http://www.echomax.co.uk/activexband.htm#1) from dealers (http://www.echomax.co.uk/Echomax_Dealers.htm) all over the world.

John Foster
Blueberry, Nonsuch 22 Sail #48

Thom
07-13-2009, 09:54 AM
The key feature disqualifying the Sea-Me from the LongPac RRC is that Sea-Me is a powered unit, and of zero value if the boat has no electrics. While it appears to be a good unit on X-band, the RRC requires the yacht have a passive radar reflector.

- rob

The RRC (again) is behind the times. You can't have it both ways, in my opinion. Either the insistence on 85 amphour batteries and associated masthead power users is outdated OR the insistence on passive radar reflectors is outdated.

Is the goal to make rules because you like making rules or is the goal to keep people safe? Is there thought about what is to be accomplished or is there just "rote acceptance" of tradition or someone else' rules? Based on what I've seen, it's the latter--but then I'm a multihull guy and you all know how untraditional we are.

BobJ
07-13-2009, 11:48 AM
The most frequent problems skippers have had offshore are with electrical systems, therefore it makes sense that key safety items not be reliant on them. The second GPS is another example - it must not be dependent on the electrical system. Ditto the primary bilge pump.

I also know first-hand that rewriting the RR&C's is a time-consuming task and at times involves wearing a target on your chest.

It's not an "us vs. them" thing.

tiger beetle
07-13-2009, 11:07 PM
The RRC (again) is behind the times. You can't have it both ways, in my opinion. Either the insistence on 85 amphour batteries and associated masthead power users is outdated OR the insistence on passive radar reflectors is outdated.

Hi Thom -

I'm confused by your post; are you perhaps dismissing reliability in pursuit of improved performance?

To make the point: the purpose of the batteries is to power navigation lights. The purpose of a radar reflector is to be seen.

If you want to increase failure points in radar reflectors then you can go with a powered radar transponder and introduce power requirements, cabling, electrical connections, printed circuit boards, and an amplifier. These elements, combined, are more useful for being detected by someone else's radar than a passive radar reflector - at the cost of complexity and increased points of failure. If any element in the chain fails then you become invisible. The statement within the rules, to date, has been that the benefit of improved radar detection does not outweigh the complexity of the system, at a minimum.

On batteries - an 85 AH battery provides a useful 30% capacity of power, or 25AH. Three navigation lights operating at deck level of 12 watts each will consume the 25AH in 8 hours; an 85AH battery is about the mininum one would want on a boat such that the navigation lights could be used at night.

An alternative to battery-powered lights are kerosene lanterns (as a kid my job was to fill and light the kerosene nav lights on my parent's sailboat - I am quite familiar with them). In contrast to the radar reflector, the rules have accepted that the benefit of electrically operated navigation lights outweighs the complexity of electrical lights - therefore electric lights are allowed and we require the minimum battery to support them.

It would be helpful to me if you would amplify what is meant by 'associated masthead power users'. What is an associated masthead power users? That has me stumped.

- rob

Thom
07-17-2009, 09:12 PM
Re: nav lights...again, LED lights use SO MUCH LESS POWER than incandescent that the 85 amphr stuff is OUTDATED.

Re: other masthead power users...VHF radio antenae, SSB radio Antenae, Stobe light (for gossake)...

When you write about kerosene running lights...honestly...are you trying for the title of "ancient mariner"?

Yeah, you have a target on your back every time you "impose" your rules on someone...I appreciate that. BUT, realize that you have accepted the mantle of "Knowing best" in the face of others' experiences and it would be "nice" to hear of an occasional acknowledgment that maybe you don't know it all (after all, I'm the only one who does :) )

tiger beetle
07-17-2009, 10:00 PM
Hi Thom -


Re: nav lights...again, LED lights use SO MUCH LESS POWER than incandescent that the 85 amphr stuff is OUTDATED.

You're absolutely right - LED lights use far less power than incandescent. Keep in mind that the minimum equipment rules are *minimum* equipment - not necessarily best or sufficient. If you want to allow a battery that is less than 85AH capacity, then you would also need to write into the rules that the boat must have LED nav lights (working on the assumption that the purpose of the battery and charging circuit is to keep nav lights running). LED lighting is more efficient than regular bulbs - but are they so much better that they are now a requirement?



geez, do you read what you write?

Yes I do, multiple times, and rework the words until I believe they convey what I want to communicate.



Re: other masthead power users...VHF radio antenae, SSB radio Antenae, Stobe light (for gossake)...

VHF antenna is a masthead requirement, for reasons that have been discussed at length.
SSB antenna is not a masthead requirement.
The strobe light, well, that's an area of contention; either you're a strobe light person or you're not. I am a strobe light person - it's can be handy at times to be wildly visible from the horizon.



When you write about kerosene running lights...honestly...are you trying for the title of "ancient mariner"?

Nope - that was to make the point that technology can march on, and can be improvement over old technology without a decrease in reliability, and therefore new technology is welcomed into a minimum equipment requirement.



it would be "nice" to hear of an occasional acknowledgment that maybe you don't know it all

Of course I do not know all; what I tend to do is research a subject to death in order to learn what I can before forming an opinion. And then I like to test theory/opinion to discover whether or not reality conforms to theory. So assume that I know little about most things, and assume that I will do a fair bit of digging around in the literature to learn from other's experiences.

- rob

solosailor
07-18-2009, 10:04 AM
The RRC (again) is behind the times. You can't have it both ways, in my opinion. Either the insistence on 85 amphour batteries and associated masthead power users is outdated OR the insistence on passive radar reflectors is outdated.No these ARE the times, you just don't like the rules. What times are we behind? The SSS rules are quite minimum if you ask me.... I also think we should be required an emergency rudder for one thing. Who has more progressive rules? It's sure not the OYRA that thinks a Farallones race is Cat 2.

Passive radar is just that, passive and requires NO power to run.... very fundamental if your single, point of failure, battery, dies. Do you have a wind vane on your multihull? If not, then you will be using an electric autopilot and an 85AH battery (I go further than Rob and say you have 50% useable capacity) to run your pilot, LED, VHF, AND autopilot, etc.... is very minimum.

Maybe YOUR the one that is behind the times because I have a 90AH battery (72AH useable @ it's rated 80% Depth of Discharge) that comes in @ 29lbs! I know it's weight that your unhappy about so call me up and spend the $$$ to get some modern technology on your boat - get with the ‘times’ would ya. That sure kills your weight issue.


Re: nav lights...again, LED lights use SO MUCH LESS POWER than incandescent that the 85 amphr stuff is OUTDATED.The running lights are only one thing you run with those amps..... again, how do you steer your boat when you are asleep? How do you make a radio call?


Again...OLD technology

Sure you can stick some clunky mainsail cutting octagon device up your mast...but you can also just put up what is essentially a whip antennae (another one) which is a radar target enhancer. It retransmits the radar sweep it receives at a cost of 350 mA. Only works in X band and some ships still have radar in S band...but still, you will get seen better by most. Sea-Me?Well the Pacific Cup, Coastal Cup, Spinnaker Cup (I’m running out of cups!), the Transpac, Singlehanded Transpac, Cabo, PV, Bermuda 1-2, Bermuda, etc. ALL require a passive radar reflector. The Sea-Me is a nice device (even though by your own statement it does NOT cover all bands used) but if there is an electrical or battery failure it is USELESS.


Yeah, you have a target on your back every time you "impose" your rules on someone...I appreciate that. BUT, realize that you have accepted the mantle of "Knowing best" in the face of others' experiences and it would be "nice" to hear of an occasional acknowledgment that maybe you don't know it all (after all, I'm the only one who does )Wow, now the SSS is IMPOSING rules on you? No they are not - you have to 'meet' the rules of an event that the SSS runs that YOU want to participate in.... if you don't want to play by the rules go play elsewhere or start up your own event.

I bet I speak for all of the people who have sat on rules, safety boards for the SSS that we don't think we "know best"... we base our decisions on experience, an open dialog, and common sense. Everyone that has been asked over the years to sit on these boards and committees have one thing in common – they are LongPac and SHTP veterans – Hmmmm…. I wonder why you have not been asked to sit on one?

OK, I'll bite, what rule has been mandated that is "in the face of other's experiences"? Who’s experiences? Your experiences? How many SHTPs and LongPacs have you done? Out of curiousity how many other long distance or trans-ocean races have you done?

Now about those Minis........!

BobJ
07-19-2009, 08:51 AM
This has become pretty negative so let's try to morph it into something more useful.

One thing that Thom's boat, Greg's boat and my boat have in common is that they are weight-sensitive. Other than perhaps the engine on my boat, the batteries are the heaviest items on board. Since Thom's and Greg's boats use outboards, batteries probably even exceed their engine's weight.

Due to poor maintenance/charging habits and a flukey battery monitor, one of my Group 27 AGM's is showing signs of needing to be replaced. Both batteries are mounted as close to the centerline as possible but that puts them behind the engine - a total of 130 pounds helping to make the stern squat.

I would like to replace the AGM's with something lighter and I know Greg has a possible alternative. What are the dimensions and cost for say, 200-210 Ah of batteries?

I would like to move them forward, like one under the forward end of each settee, but there's only 8" of height under there.

This also makes me wonder how long battery cables can be. I see "battery relocation kits" online but these are designed for car racing.

As skippers start looking at that second battery requirement for the SHTP, what are the current options?

Thom
07-20-2009, 02:10 PM
One option that works well on my boat...but I only have two "hotel" loads; nav lights and autohelm. Since keeping a cable system (and associated line losses) as well as maintaining the cable connectors, switches, distribution panel, etc. working in a salt water environment, I eliminated all of that from the boat and have instead purchased batteries of the appropriate AH size for each hotel load. I have spares so after 24 hours of use the spare could be put into use while the other is charged. All have the same connectors so they become interchangeable. The same solar panel(s) charge any of them.

YMMV and your boat probably has a lot more hotel loads than mine (wired VHF, strobe light, SSB, instruments, refrigerator, air conditioner...???). It might be impractical for you to have little batteries scattered all over the boat and might be best to keep the one large bank of batteries that most boats have. But this system works for me with a lot less maintenance than the previous "traditional" system.

Thom
07-20-2009, 02:21 PM
You are absolutely correct. I don't have to live by the SSS' inflexibility and choose not to do so. While it may have been "nice" to go to HI in a "group parade", sticking to SSS' rules have the potential to make it more unlikely for me to arrive safely. I'm no fool, it's safer to go alone (or not at all). Currently it is the "not at all" because I haven't found a good autohelm that I feel safe driving downwind with.

tiger beetle
07-20-2009, 08:31 PM
Currently it is the "not at all" because I haven't found a good autohelm that I feel safe driving downwind with.

Have you checked out the pilots that NKE has? They certainly have a solid reputation in the small fast boat crowd (mini Transat comes mind) - perhaps such a pilot would do well on a multihull.

- rob

AlanH
07-22-2009, 12:04 PM
You are absolutely correct. I don't have to live by the SSS' inflexibility and choose not to do so. While it may have been "nice" to go to HI in a "group parade", sticking to SSS' rules have the potential to make it more unlikely for me to arrive safely. I'm no fool, it's safer to go alone (or not at all). Currently it is the "not at all" because I haven't found a good autohelm that I feel safe driving downwind with.

Hmm. I have to ask... if you perceive that the SSS is inflexible and out of touch, and if you feel that at least the Hawaii race, and probably the LongPac, if not ALL the SSS races are "group parades" and inherently unsafe, then..

... why do you post here? :confused:

I mean, not that you CAN'T, I'm just not sure why you'd want to.

Thom
07-25-2009, 08:40 AM
A couple reasons I post here.

First is that I am donating 2 years of effort as a SSS officer-anytime I am part of an organization I seek to make it better. I'm sure you feel the same way about things you devote your time and effort to.

Second is that during the first year as an officer, I noted a distinct pattern of inflexibility. Very few question why we are doing things or requiring things nor seeking a more modern alternative. While traditions are nice, I don't ever expect to have to navigate celestially with a sextant ever again (where would I get the pubs, let alone store them?), nor add oil to my running lights so they keep burning, nor make rope from oakum, nor pull into an island so I can make "beer" so I can return to sea with fewer worries about scurvy, splice a mast with a local tree trunk....

While we represent current style "adventurers", we never will have to undergo the hardships of the folks from previous centuries. But the key word is "adventure"-if that's not one of the things this club is about, maybe I misunderstood our mission statement. One of the key characteristics of an adventurer is a willingness to accept risk--but that spirit seems to be diminishing. My posts are driven toward advocating a return to reasonable risk taking instead of rote tradition. Perhaps I'm just impatient...

BobJ
07-25-2009, 11:09 AM
Thom, would you be more specific? Sextants, oil-fired running lights, oakum and tree trunks are not required for our races.

In another post you generally questioned the battery requirements. I've done an energy budget for "Ragtime!" and had the opportunity to test and update it over several weeks in the ocean. Even though my boat lacks many of the amenities of larger boats in our fleet, has all-LED lighting and is easy on autopilot loads*, the SSS's battery requirements are barely sufficient in my experience. (*Except when I'm having spinnaker issues!)

On one hand you want "more modern alternatives" and on the other you want a "return to more reasonable risk-taking." Specifically, how do reconcile those two desires if you are a race committee chair updating a set of race rules?

I'm not trying to call you out but I'm having a tough time understanding what's eating you - maybe we need to get a beer and talk about it.