New Boat 4 Sled

[pogen]

A head's up to all those equipped with AIS Class B transponders:

Yes I recall the part about VTS being true, and me being shocked by it.

Almost no recreational sailboat will have Class A -- the power draw is too great and the expense is much higher...

It may be that some commercial shipping is filtering out Class B targets, but I've certainly been seen in the Gulf of the Farallones approach area by ships. It's a great comfort to hail them and be told "yes I see you".

Some people get mixed up and think Class B refers to the receive-only units that are now cheap and popular. That's not the case -- Class B is transmit/receive, but at a lower rate (fewer times per minute), less broadcast RF power, and with less data than Class A.

[pogen]

I was on the watch for pythons:

Just be sure your python boot is on, and not too tight.

[Dazzler]

It is our obligation to keep a lookout, and not assume you are being seen electronically by the other guy.

Sled's last comment is probably the most important take-away.

To clarify what we learned on our May 16 tour of VTS and CG Golden Gate's communication center, our tour was arranged by the YRA and was conducted by F. Scott Humphrey, VTS Training Coordinator. Questions asked and answered:

1. Q: Can you see our fiberglass sailboats on VTS radar.
A. (Scott) No, our radar is tuned to see big ships.
I suspect this was an over simplified answer, and I further suspect the real answer is, "it depends..." Such factors as sea state, distance from the radar antenna and if the vessel has a good radar reflector would influence reception, and ability to identify the radar signal. Jackie's experience suggests that in some conditions they can see you on radar, but I wouldn't count on it.

2. VTS "sees" on their electronic chart screen commercial vessels that are required to have AIS Class A transceivers. They currently are NOT equipped to receive AIS Class B signals. Plans are in the works to upgrade their system to receive AIS Class B and they hope to have that functional by the end of Summer. One can't help but wonder about current funding issues/ challenges
.
3. Q. It has been rumored that AIS Class A user can filter out Class B signals. Is that true?
A. (Scott) Yes, but that doesn't mean that they always do. Again, they may or may not see you. Don't count on it.

4. Q. The publisher of Lat38 not long ago recommended AIS Class B user should silence their transmissions in the Bay as they cause chart plotter clutter.
A. Scott answered emphatically NO do not silence your AIS Class B in the Bay. His reaction to the question suggest that he thought the idea some what ridiculous.

5. Regarding the VTS OFFSHORE SECTOR (VHF 12) it was strongly recommended that vessels listen to the Offshore Vessel Traffic Advisories on VHF FM channel 12 at minute 15 and 45 each hour. VTS broadcasts the position (true bearing and range from the San Francisco Sea Buoy), true course, true speed and waypoint ETAs for each VMRS user in the Offshore Sector.

6. Regarding communication with VTS by recreational vessels, Scott made it clear that they have no problem with us calling in to ask questions or report our position. It should be noted that the VTS INSHORE SECTOR (VHF 14) extends all the way to the Pilot Station.

7. Regarding communication with other vessels that are within the VTS system, those vessels have no obligation to monitor VHF 16. They are required to monitor VHF 13 and that's the way to hail them.

8. VTS has another interesting tool in their kit: high definition video cameras that they can aim. The comment was made that they've seen "some pretty weird stuff out there." So, keep that in mind.

The tour was very educational and I can highly recommend it. If there is sufficient interest among SSS members, we could have our own tour.

Tom

[sleddog]

This just received from a SF Bar Pilot with 30 years on the job:

"Ahoy Skip
I track only Class-A AIS equipped vessels on my laptop. That being said, there must be a number of pleasure craft and fishing vessels that have Class-A equipment because they do show up. The ships are usually tracking Class-A only as well on their electronic chart displays and AIS equipped radars.

As you surmised, the clutter that would result on the screens by seeing both Class-A and Class-B targets would be overly distracting ... and a detriment to the safe navigation of the ship ... not a convenience."

FYI: from reading the VTS manual, it is my belief that SF Bay VTS has a 38 mile range seaward on its radar situated atop Mt. Tamalpais.

[mike cunningham]

For what it's worth, I communicated with several ships during the SHTP, all of these contacts were well offshore. I could see them so I thought I would reach out and make sure they saw me. I always asked if they saw me on radar and on AIS. I was happy to hear that in all cases they saw both. That doesn't mean they are actually watching them but at least my contact was visible to their equipment if they were paying attention to it. Of course I was flying a radar reflector per rules so that would help on the radar side of things.

I wonder of they may tweak their AIS to look for all targets, class A and B, when they get offshore?

My Son, who is a merchant mariner, tells me radar can be pretty noisy and the bridge is more attuned to AIS when they are at sea.

[sleddog]

For those who have followed his adventures, Howard Rice is as tough and skilled seaman as they come. Howard's recent experience attempting to round Cape Horn on his self-built and well prepared 12 foot Scamp SOUTHERN CROSS is particularly sobering. While tied up in a small cove, Howard was "attacked" by Tromba winds, multiple small tornados of extreme violence, that capsized SOUTHERN CROSS and blew Howard off his boat. His survival was not assured as he blew downwind, attempting to swim to shore in frigid water.

Howard's story is still unfolding. https://sagemarineblog.wordpress.com/tag/howard-rice/

[Tchoupitoulas]

I recall during a VTS tour they said that as soon as you hit that VHF mic key, their gear can triangulate a position from multiple antenna if within sight. So I guess that's another way they can see you.

[sleddog]

WEE WINN, besides her good looking color, had something underwater we take for granted 125 years later. WEE WINN (24 feet LOA) was designed and built by Nathaniel Herreshoff of Bristol, RI in 1891. She was the first boat with a modern fin keel, and proved so fast that she was banned from racing.



Fin keels pretty much stayed similar in design until 1976, when Doug Peterson increased the depth vs. length (higher aspect ratio) on his breakthrough One Tonner GANBARE. IE, fin keels on state of the art race boats became deeper than they were long....

It's good to see WEE WINN is undergoing complete restoration at the Herreshoff Marine Museum, where she was originally built. https://therelianceproject.com/tag/h...marine-museum/

Candy apple red is a cool color.

[H Spruit]

It is interesting to me that fin keel spade rudder concept was outlawed 1891.
Because when Rod Park commissioned Bill Lee, with the help of George Olson, to build Panache, (a 40 foot ultra lite with fin & spade)
They announced to us locals that that the goal was to compete in Transpac and to be a complete success the needed to get banned.
Panache was also painted Candy Apple red.
They did not get banned but were slapped with a rating penalty to prevent them from ever wining.
Of coarse Rod, and Bill led a protest to the transpac committee.
The committee answered the protest by sending Rod back his entry form,with check attached, and explained that the race was an invitational event and they were not required to accept entry, and offered to return his entry fee.
Panache did go on the race and I think they corrected out to 8th.
Anyway I continue to be impressed by how far ahead of the establishment thinking the Herreshoff clan were and how much what we were doing in the 70s paralleled their work.

[AlanH]

Replacement B-25 keel made by Custom Composites.



I've always wondered how a super-skinny keel strut worked. It doesn't have enough chord to provide much resistance to lateral slippage. I assume that it works by generating a whole lot of lift, which of course only works when the boat is moving at some sort of speed.

Comments welcome!!