Pull down stability test

[Kiteroa 8]

I did a pull down test on WT after I got my ORC cert a few years back. I couldn’t believe the stability figures I was given and since I was about to do a new rig I wanted realistic numbers. I took the boat over to the super yacht berths at GH, found an empty one and tipped the boat over there. I had a loop around the mast tube at the hounds where the rig was well supported, and a 6:1 purchase and a load cell attached to the dock. Getting to 35° was easy done. Most normal type yachts reach RM MAX at about 60deg and that’s when you have a bit of load on, so as soon as you see the load cell load dropping, you’ve passed RM MAX. It’s important to keep the pull down line at 90° to the mast tube for an accurate reading though.

[Guest]

Thanks Rocket and WT. I'll try to remember all that as it happens.

I have a big 5:1 system and a towbar

 

I suspect with our shortage of form stability it shouldn't be to hard.

 

Be interesting to see where she'll start to drop off in loads. Been blown over a quite few times and she does go to a spot (a well leaning over spot but the windows are still dry) but then just stops there and seems to have knot the slightest desire to go further. She'll sit right over there quite happily, almost tamely, until the wind tapers back. To get it further I'd suspect we'd have to be over there and then cop a big wave right at that moment, I have never once had a feeling she was going down and was going stay down, one I've had on other boats over the years.

 

That does exclude the couple of times I've put the mast in, those were all rather nice and large wipeouts. Zero sign she wanted to go further even then. Once was with the kite up and the boat was fighting the kite very hard, she'd come up and the kite was just holding her down. As soon as the snap shackle broke (thank f*ck for that I was solo at the time and wondering how I was going to get it down) she popped up like a cork.

[PaulR 3]

Anyone know how to set up the boat for a pull down righting check test?

 

I see nobody has really answered some of the basic questions.

 

1). Get the Insurance Company OK to do the test FIRST.

 

2). Ask them along and suggest they supply the rum.

 

3). Remove all valuables, instruction books, ships papers etc

 

4). Review the video above. I would suggest putting in the wash boards and closing all hatches would be useful.

 

5). Look at your engine and for inboards, taping the oil dipstick to stay in place is helpful. Some engines may prefer to have been hauled over the OTHER WAY

 

6). Remove any spare oil, cooking and suntanning as well to reduce the mess potential.

 

7). Having the odd bow & stern lines will allow you to turn the boat for any windage issues.

 

. No doubt all your spare anchors, chains, batteries etc are still safely secured from the last SIMRAD race

 

9). Block off any leeward cowls & vents

 

10). Remove all partially used food stuffs from galley.

 

Yes I would like to be there

[wheels 543]

A plus with doing this, the things you lost down in the bilge may resurface.

[SloopJohnB 322]

get a dingy and clean one half of the bottom.

[PaulR 3]

get a dingy and clean one half of the bottom.

 

 

AND . . . antifoul one side today whilst the sun shines

[Guest]

A plus with doing this, the things you lost down in the bilge may resurface.

Knot sure a 30mm airspace between the floorboards and hull quite cuts it as big enough to call it a bilge.

 

Looks like the lads are in Bayswater with a barge that has a 15t crane on it. Any bets what she weighs? Don't bother sussing my PHRF Cert, all the numbers on that were copied off some place I found on the interweb so I have no idea if they are right or knot

 

Between 2300 and 2400kg is my guess, in race mode.

5000kg when cruzing and the frontbums have loaded on all their crap

[wal 27]

Also - is your battery a sealed unit?

[PaulR 3]

It's Sunday Morning . . . and KM's update is expected . . .

 

or has he knot adjusted his clocks

[wheels 543]

I think the test is this afternoon and the weather is looking a little bleek here, so not sure of intentions. I was going to txt him and see whats happening.

[wheels 543]

Yep confirmed, pull down postponed due to wet and yucky weather.

[Guest]

Postponed due to wet, yucky and large nite. Also hope to have data logger available next week so can measure everything as it happens. We have a couple of weeks of window.

 

Had a quick little play yesterday arvo and now in 2 minds just what load we'll have at 90 degrees. Can get her over a fair way quite easy but then she really starts to play hard to get. Having knot a lot of form maybe that primordial keel has more righting balls than 1st thought. The Turbos must stack up real huge I'm thinking.

 

Don't suppose anyone knows Pepes number/s. She must have done something for the RNI wouldn't she?

 

Yes Wal, the battery was specifically purchased as a sealed one, it is a Ross boat so lean over proofing was in mind at the time

 

Go Blacks, Sux snails Froggies

[Addem 95]

I just spent an hour reading through this post eagerly anticipating the climax and then on the last page ....nothing.  .  

 

KM, did the test get  done?  I'd be keen to hear as we are investigating doing a keel job similar to the one Meister has done, which effectively is similar to the Ross 930 conversion.  We're getting Bakewell-White to do the design and calcs.  I'm wondering whether this will make it necessary to do a pull down test to get our Cat 3 cert back?  

 

If so, we'd be keen to hear how you got on, advice,comment, whatever, about how the keel mods affect your certification.  Can start a new thread if you like. 

 

(and, yes, Willow, I know we have probably got rocks in our heads, but there is no harm in wondering and spending the time on this is more edifying than watching cricket right now).

[markm 30]

Addem, expect BW would be able to produce the relevant AVS number and any documentation for you.

[Battleship 100]

(and, yes, Willow, I know we have probably got rocks in our heads, but there is no harm in wondering and spending the time on this is more edifying than watching cricket right now).

 

Haven't we all got rocks in our heads, I am in the process of a keel update on a larger boat myself, doesn't make any sense except that it's fun. 

 

It does pay to go into these things your eyes wide open, plenty of people have started a project and then realized it was to hard or expensive or both and sold the mess at a loss. Was playing devils advocate.

 

You are a long time in the ground so why not.

 

As for the pull down test you wont need one, just talk to Mr BBW he can do a calc for you and you will probably find the boat will pass quite easily for cat3 and with the new deep keel it will be even better.

[Addem 95]

And here I was thinking you were trying to put me off.

 

We've certainly got our eyes open. Not yet bobble eyed but prepared. Learning a lot along the way too, so that alone is worth the effort.

[Addem 95]

Thanks KMM. It's all good to hear. Does make wonder why you had to do the test though.

 

But the main point established here is the

At we shouldn't have to.

 

I like the open transom you've done too.