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Old 30-05-2005, 12:01   #1
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new boat problems

Hi, we have just purchased a steel yacht and are very happy with most parts of it. However in the Marina when it is tied up we find it heels over when hit by gusts of wind considerably more than other yachts around it. It tends to heel quickly and recover quickly. It is 38 feet overall, and draws 5 foot. It has 4 ton of ballest and a long keel. Hull and decks are steel which is popular down here in New Zealand. The funny thing is that it sails really well for a heavy displacement yacht. Can anyone provide me with a solution or tell me what my problem is? It does have a fairly large mast extrusion which of course will add to it's windage. The previous owners had it filled with cruising equipment which is currently not on the boat and it is my suspicion that with this loss of weight in the bilge areas etc has added to this problem. Look forward to someone explaining this to me.
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Old 30-05-2005, 16:15   #2
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You could employ strategies similar to that demonstrated by the Davis “Rocker Stopper”, or the Magma “Rock-N-Roll Stabilizer System” (R10-707 or R10-702)
or as variously described as “Flopper Stoppers” etc. (“Google”).

DAVIS: http://www.davisnet.com/marine/products Then (Rocker Stopper under) Docking & Fishing

MAGMA: http://www.magmaproducts.com/R10-702_707_Assembly.PDF

Even just a couple of buckets, hung over each rail, might help some.

See also “Roll Motion of Yachts at Anchor” - by K. Klaka & M.R. Renilson
http://www.curtin.edu.au/curtin/cent...at/2002-08.pdf

HTH,
Gord May
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Old 30-05-2005, 16:35   #3
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Heel

Your boat may have less form stability than the others. Form stability comes from a wider beam to length ratio.
Positive stability comes from the ballast hanging from the bottom.
What is the beam of your boat, what is the total weight and the weight of the ballast ? Small boats around 25 feet may have more beam to get room inside and they use the beam for stability, but the stability diminishes as the boat heals a lot. So these boats have good stability initially, but it disapears later. Sounds like you have the opposite, and that is what you want.
Michael
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Old 30-05-2005, 20:52   #4
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What is the Rigging?? Steel mast by any chance??? What is fitted to the top of the mast? Where is the radar?? Is there a Pilot house? and what sort of weather protection has been built on it/above it/around it/yadda yadda? Do you have a furling Headsail? Is you main bundled on the boom with a boom cover?
All these questions add up to windage aloft. In other words, there is a lot of leverage high up above the centre line the boat rolls upon. You may have 4 tonne of ballast, but it is 4 tonne to the righting moment, when the boat is laid horizontal. Any less than horizontal and weight applied to the righting moment decreases. So it take very little energy at the opposite end of the scale, i.e. Mast, to move pivot the boat. The centre of that movement, becomes the fulcrum point.
Now back to the steel mast part. Rig mass can be a positive as well as a negative. Mass provides resistance to movement. So in a heavey sea, that mass can be your alli. The negative aspect, once mass is moving, it resists wanting to stop. So in a Marina, once a wake or wind moves the boat, it becomes harder to stop the movment.
Now one step further. What about weight distributed below. Such as, where are heavey objects like batteries and fuel tanks situated. Once again, when heavey objects are centred directly, they add very little to the stability. The weight only has an affect on stability, as that combined mass down below, is swung to the side. But that mass below is what will give you a greater righting moment, when it is pushed out to the side when under sail. The weight from heavey objects, will have little affect if it is at Waterline or even less above it.
The next point is draft and the shape of your hull. A deep slender shape hull will act against the mass of water, and help reduce movement. A round hull, with less keel depth, will have little lateral resistance. That comes down to design and what the designer intended of the craft.
So don't panic. The quetions you need to ask of yourself and answer, can I reduce windage aloft? Thats about all you can do. Maybe look at weight distribution, and ensure as much of those real heavey objects are as low down, below the waterline, as possible.
Look att eh waterline of the hull. Is it sitting right? Not too much weight forward or aft. Especially bow down if you use a lot of anchor and chain. Or aft heavey if you stow heavey gear to the rear. The boat needs to rest as close to level as possible. This has a big affect on sailing ability as well.

NOTE: I am jo expert on hull design and have a lot to learn on sailing. The above is just what I have learn't thus far, and I stand to be corrected.
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Old 31-05-2005, 02:07   #5
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Interesting - thanks for your information. to make things easier here is the exact design info for the boat.

Koopmans long keel - rolled round bilge hull

LOA - 11.40 METRES - 38 feet
LWL - 9.10 METRES - 30 feet
BEAM - 3.42 METRES - 11.22 feet
DEPTH - 1.6 METRES - 5.25 feet

Approx 4 ton of lead in the keel

The mast is alloy and of a fairly large extrusion for the size of the boat.
Their is no hard dodger - only soft
Furlers = yes - set up as cutter rigged hence 2 furlers
Main is bagged on boom

All batteries and fuel is stored in the keel below the water line.
Chain and anchor is currently on the dock off the boat.
We have currently removed everything off the boat hence it is sitting up on it's waterline by approximately 10 inches, and maybe this is having some effect on it's movement. The marina we are in gets a lot of wind. The boat is fine in winds up to 20 knots but last night and yesterday we had 35 knots plus which is common for where I live.

I can only reduce windage by removing the spinaker poles off the mast and reducing the number of halyards aloft. I don't want to remove my furlers but currently their are no sails on these anyhow - only the foils.

We do find the boat sails fairly well. It tends to heal only to a point and then stays there - it takes a lot of wind to push her over further. We only have to put 1 reef in at 18 knots. She seems to point ok for a steel boat and can maintain 7 knots on the wind which is ok for us. Me and my wife are in our late 20's and following our dream of sailing around the world. We will be hopefully leaving in 4 weeks time for Fiji.

Thanks in advance for any advise/info. I've surfed this board for a few years now and found some very useful info over the years.
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Old 31-05-2005, 05:51   #6
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Were are you Southernman? I am based in Havelock and it gets brezzy here too.
10" above waterline, thats a lot and will make a big difference when she settles down to cruise weight.
Ours weighs in at a total of 26ton and our weight moving around is insignificant. However, a real hard gust will still roll her about. I have been on a 50ft Alloy yacht and it was so light, it moved around under foot like a cork. It felt horrible.
All the best for the trip to the warmer climate.
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Old 31-05-2005, 18:27   #7
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I noticed there was no mention of the displacement weight or how much freeboard. Both of these will contribute to a windage problem.

Also the draft of 5' seems a little shallow for a 38' Pacific vessel. Although, 4 tons of ballast seems reasonable for that draft.
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Old 31-05-2005, 19:20   #8
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yeah the draft is on the light side but of course it means i can get into all those nice anchorages. Allan - I'm in Wellington but I often get down to Havelock for work so i'll check out your boat sometime! We displace around 11 tons so our boat is a little lighter than yours!

I'm sure you guys are right in that once it is fully loaded with equipment again she will drop in the water! I checked the freeboard last night again and it is actually around 20cm above it's waterline! On the freeboard question she is a classic Dutch Koopmans Steel yacht so the freeboard is not huge by modern standards - she is certainly no Hunter or any of those other production thingys with nothing in the water and everything above it!

Have I mentioned that this yacht was built in the UK and has sailed out to the US and the Carribien and then througth the Pacific down to NZ already - so you can see I don't have any real concerns about it's ability to get out there and sail oceans. It's just a little annoying to live aboard.

The other thing is that the boat is in a berth that is far too big for it and hence the lengths of our mooring lines are quite long so it gives the boat quite a bit of room to start 'sailing' around on them and then pull up on them which is a little annoying.
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Old 31-05-2005, 22:27   #9
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Initial stability

Only a competent designer having the design "stations" etc available would be able to definitively comment regarding what you are describing as an initial stability problem. If the initial stability is low then any windage aloft will cause the boat to heel more easily than a boat with high initial stability.

If you have a mast with a large cross-section and if it is 50 ft off of the deck (or more) for your 38 footer you will have an initial stability problem which does not necessarily screw up the final stability very much. If that is the case then reducing the mass below decks will not do much to alleviate the problem...only affect the magnitude and action of the heeling moment. You will find that, compared with boats with higher initial stability, that you will also need to almost always set a sheeted in main (reefed or otherwise) to avoid the unpleasant acceleration of the roll.

If that is your problem then I have lived with it on another boat. The boat handled wonderfully even in a hurricane yet I always set the main when "out" except when in the hurricane when I had NO sails up, the downwind pole I had lashed between the mast and the headstay because I didn't want to take the scary effort to stow it back against the mast. The wind passing from astern made the boat stand upright with good stability until the wind dropped to 55 knots over the boat then I had to set a storm sail.

I agre with Gord that you should check out an "anti-roll device" (Flopper-Stopper is a brand name, not a generic description). I carried two yet, at anchor, discovered that only one was required to radically reduce the acceleration of rolling at anchor. Remember that the amount of roll means almost nothing, it is the ACCELERATION of the roll which makes you uncomforable and sets things flying off of the table down below.

Use your downwind pole guyed outboard fore and aft to set an anti-roll device from a spinnaker halyard run through the end of the pole to the anti-roll device. I am partial to the design which is a "book" that folds flat and opens when the boat tries to roll. The back of the book is a hinge. Bungee-type cords close the book on the back roll and the bridle is placed on the pages of the book so as to prevent the back (hinge) from breaking past 180 degrees. Don't remember the brand yet have seen it around.

Regards,
Rick
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Old 09-06-2005, 08:53   #10
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problem solved

well problem solved. On Sunday it blew 35 knots again and this time we are fully loaded up again with supplies and 4 people having a cup of coffee - motion of boat much better! We still have about a ton of stuff to put back on board and then we will be ready to leave for Fiji. It seems that by dropping the boat by 5 inches in the water it sits much better when it blows!
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Old 09-06-2005, 08:57   #11
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Good to hear. Hey have a great trip up to those warmer waters. I eny you. I'm frezzing my butt off down here in Marlborough. We had a -5 frost here lastTues.
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Old 09-06-2005, 09:30   #12
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havelock

Hi allan - I went through Havelock this afternoon and I'm on the ferry heading home now! pitty I didn't have any time to drop in but I will next time I'm through. We won't be going to Fiji until my work is finished and if it's too late in the year we will head to Aussie (Cairns) instead.

You have a Hartly ferro don't you? My old man is maybe looking to buy one - you don't know where a good one is do you?
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Old 09-06-2005, 20:34   #13
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I possibly do and I think it is up your way. At least I do have a mate in Picton, that specialises in Ferro Brokerage, and he is very trust worthy.
Be aware of one sitting in Nelson for sale. It has some nasty history.
Email me when you are ready and I will help if I can.
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Old 10-06-2005, 01:37   #14
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All the kings horses…

This was a very entertaining thread. Many advisors, many solutions, much theory, little application.

Very glad you fellows aren't physicians.
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Old 10-06-2005, 06:35   #15
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Not sure what you mean by little application. The answer to the actuall problem was given within the threads. And a physician wouldn't be giving a diagnosis based on little information via a bullitin board post. So what would you expect. Plus, I didn't see you thoughts put forward.
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