New toy in Auckland...

[DrWatson 382]

2 minutes ago, Steve said:

Yes. And it was blowing. I think if you had the depth, keel down might be easier. 
But not that bad really. 

Backwards is easier than forwards... going forwards, with the keel up when going slow, the bow is blown off almost instantly (not helped by the transfer of mass aft which further reduces lateral plane forward of the mast). It's no place for fainthearted helming or manoeuvring.

[RushMan 31]

Shaggybaxter from SA hit a whale, the keel popped, no damage other than a whale looking for Panadol.  Reset the keel and continued their sailing.

From his account the system works

 

[Island Time 1,284]

9 hours ago, RushMan said:

Shaggybaxter from SA hit a whale, the keel popped, no damage other than a whale looking for Panadol.  Reset the keel and continued their sailing.

From his account the system works

 

Interesting and encouraging, but then all impacts differ - glancing blows, speed of impact, immediate stop or less violent etc. No boat can survive anything that could happen. I like the Pogo's, and as I said above, I'd consider one if I ha the $$

[Steve Pope 253]

12 hours ago, Island Time said:

Indeed, however the pressure induced by a solid keel impact, will create a shock, transmitted back thru the lift mechanism.

In a severe impact it's likely to break the ram mounting points as the pressure cannot be released through a valve sufficiently quickly - fluid is not compressible etc. This issue may be designed in, with a "fuse" in the system to allow the keel to be pressed up as part of the shock absorption design... or not.

I know with my (non) ballasted swing keel(s) that they lift very easily when the bottom gets too close, They also will hold you in place for shortish periods and if the aft one is in the mud as well you don't swing.  Rather like lowering a spud or 2 as they do on dredging and mooring inspection barges.

[Island Time 1,284]

One of the issues that can be seen with that type on some vessels Steve, is that when sailing fast, if not locked down, the water pressure can move them aft, changing the boat's handling....

[Steve Pope 253]

23 hours ago, Island Time said:

One of the issues that can be seen with that type on some vessels Steve, is that when sailing fast, if not locked down, the water pressure can move them aft, changing the boat's handling....

Luckily perhaps, Gwalarn doesn't do fast, at least by todays standards. I Have seen 9 knots for a second or two while surfing. Average cruising speed for all ocean passages to date has been 4.5 knots.

I change the handling by raising or lowering the aft board and raising the primary board when running downwind.

[Steve 40]

1 minute ago, Steve Pope said:

Luckily perhaps, Gwalarn doesn't do fast, at least by todays standards. I Have seen 9 knots for a second or two while surfing. Average cruising speed for all ocean passages to date has been 4.5 knots.

I change the handling by raising or lowering the aft board and raising the primary board when running downwind.

It would be great if that was legal while racing.  The weight would shift aft nicely.  

If only we could then push the keel forward for light airs as well and get those big bums out of the water. (and make it legal of course)

[Steve Pope 253]

46 minutes ago, Steve said:

It would be great if that was legal while racing.  The weight would shift aft nicely.  

If only we could then push the keel forward for light airs as well and get those big bums out of the water. (and make it legal of course)

Both my boards are unballasted (20mm alluminium plate) so they don't alter the weight distribution when lifted. All ballast (lead) is in the hull below the water tank.

The original "Trismus" drawings had a dagger board in the forefoot as well as the primary and aft lifting ones. It didn't make it into the eventual design though.

[Fish 0]

1 hour ago, Steve said:

It would be great if that was legal while racing.  The weight would shift aft nicely.  

If only we could then push the keel forward for light airs as well and get those big bums out of the water. (and make it legal of course)

Surely if you declare movable ballast on your handicap, it is legal?

Canting keels and water ballast are all forms of this. You may get penalised excessively by the handicap rating, but if its declared surely it is legal?

[Steve 40]

Just now, Fish said:

Surely if you declare movable ballast on your handicap, it is legal?

Canting keels and water ballast are all forms of this. You may get penalised excessively by the handicap rating, but if its declared surely it is legal?

Bit of a fine line between movable ballast and a lifting keel I guess.

I think it's probably a bit of a hangover from the trailer yacht days when pulling the board up off the wind on your 780 was an advantage but also bloody scary at times.  Now, in most SI's you will see that all keels must be in the locked down position for the duration of the race.  Canters have a separate rule.  Bit of a pity as I see an advantage there waiting to be exploited.  

[Steve 40]

SSANZ NOR

 

2.1 Racing rules shall be changed as follows.

2.2 Yachts with lifting keels shall have keels locked in the down position and not moved whilst racing. This changes RRS 51.

2.3 Yachts with movable ballast, in the form of a canting keel or water ballast, may move that ballast to increase or decrease weight, or to change trim or stability. This changes rule 51.

2.4 Movement of sails not in use while racing is allowed; however, sails not being flown must remain within the boat’s lifelines. This modifies RRS 51 only as to the movement of sails.

2.5 Rule 52 shall not apply to the adjustment of a canting keel or water ballast.

 

Bugger

[Deep Purple 520]

8 hours ago, Steve said:

I think it's probably a bit of a hangover from the trailer yacht days when pulling the board up off the wind on your 780 was an advantage but also bloody scary at times

Yep - I remember blasting down the back of Rangi in a Black Heart Rum race in a 780, we always wound the keel up, 1 foot of plate out the top of the case.

 

As an aside, and I'm no engineer but I would have thought it odd that the ram when under the most load is fully extended.  But I guess the most strength and resistance to a knock would be with the ram retracted which it is when down.

[markm 30]

From what I recall, S.I. amendment to lock down centreboards became fairly standard in NZ after Astrotraveller (Lightning 7.5) had a moderately serious roll one breezy squaddy winter series race in the late 80s.
 

[chariot 244]

Not a new toy in Auckland but I see a new toy arrived in Whitianga. Tazzy Devil now in Mercury Bay

[Steve 40]

Pics please.

[Steve 40]

Starting to sound like Mercury Bay’s the place to be for good racing.

[Cantab 341]

On 4/12/2020 at 11:44 AM, Steve said:

Yachts with movable ballast, in the form of a canting keel or water ballast, may move that ballast to increase or decrease weight, or to change trim or stability. This changes rule 51.

So are those pogo type keels canting fore and aft, movable ballast, or not? They still meet stability requirements "canted aft". 

It tends to be the pt. stb. canting boats that get into trouble when the mechanism breaks or they fall off. 

Altering trim by moving it back seems to be allowed. 

Maybe rules got left behind by technological development again. 

[Steve 40]

13 hours ago, BOIGuy said:

So are those pogo type keels canting fore and aft, movable ballast, or not? They still meet stability requirements "canted aft". 

It tends to be the pt. stb. canting boats that get into trouble when the mechanism breaks or they fall off. 

Altering trim by moving it back seems to be allowed. 

Maybe rules got left behind by technological development again. 

       See below

          Pulling the keel up drops the stern like putting a All Black tight five on the back of the boat.

I have no evidence to say that this will work off the wind in a blow but it would be great fun to give it a try.

• Even with the keel lifted, the Pogo12.50 could be classified as a Class B Design Category under ISO 12217 (minimum required AVS= 130o-0.005xDisplacement = 130o -0.005×5500 = 102.5o >95o)

[DrWatson 382]

The keel doesn’t count as moveable ballast in rating for a pogo, but most handicapping (except Phrf) kills them dead - 3m draft is a big penalty.

lifting the keel up will result in a net loss of control and a lower boat speed - if you look at the shape when the keel is up - it’s a hydrodramatic tradgedy

[DrWatson 382]

13 hours ago, Steve said:

I have no evidence to say that this will work off the wind in a blow but it would be great fun to give it a try.

I mean I’m all for experimentation, but Let’s try in someone else’s...