Ballast for Centreboard Senior

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Martin Norris
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Location: Cumbria

Ballast for Centreboard Senior

Postby Martin Norris » Wed January 28th, 2015, 6:05 pm

HI, I started work on building a Senior last year but due to a combination of circumstances work ground to a halt.Anyway determined to make a good start in the spring.Something that has been puzzling me and I can't find any reference to on the plans CD is the question of ballast for the Centreboard version.

Please can anyone enlighten me.


Thanks very much,

Martin Norris

Bob Puzey
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Re: Ballast for Centreboard Senior

Postby Bob Puzey » Wed February 4th, 2015, 8:31 am

Martin,
I'm very interested in getting a response to the question of ballast as well. I've had my centre board Senior for about three years now, but only been on the water twice due to other projects getting in the way. I am hoping that this year will prove different and I can get a few miles in.

The dinghy cruising association recommends 14 lbs (6.35 kg) per foot of boat length (not sure if that's waterline or overall) which equates to approximately 225 lbs (100 kg).

I have added a box under the floor between the centre board casing and companion way. It currently holds 40 kgs of ballast (steel shot in 1 litre milk cartons - 5 kg each - I've used the milk cartons so that I can move them at the moment, eventually I'll encase in resin). I am intending placing 30 kg below the floor each side of the center board casing. I've sailed once with this configuration, but only in light winds, so it didn't really prove much. My reasoning behind placing a significant amount of ballast aft of the centre board was to help counter weather helm.

It's worth noting that the dinghy cruising association also recommends 1 stone of crew weight per foot of boat length.

I would also be interested in hearing from anyone that has capsized a centre board Senior. How easy are they to right? I have added 180 kg buoyancy high in the cockpit and transom lockers.

Bob

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Re: Ballast for Centreboard Senior

Postby Eventide Owners Group » Wed February 4th, 2015, 9:28 am

Hello Bob and Martin,

The Senior comes in several guises and the centreboard is the one that some claim is the easiest to launch and recover and the fastest. but there is a down side. it was designed with no internal ballast and supposed to be sailed like a large dinghy!

fine for sheltered water.

I would have thought 200lb of internal ballast would be a great addition, properly secured.

The Senior in the bilge keel version has a cast iron 160lb keel and 2 stubby wooden bilge keels, OK for gentle pottering and launching and recovering, but the sailing performance is poor.

There is another version that the designer drew and has been the most successful, that is the extended bilge keel version. The same main keel with 160lb of ballast is used, but the deadwood above it deepened by 6". Then the wooden bilge plates are replaced with deeper 3/8 or 10mm steel, galvanised plates.

The difference from the normal bilge keel version is chalk and cheese! She sails to windward, she still dries out easily on a beach and is not much more problem to trail as she just needs another 6" of water. The deeper ballast makes her stiffer and grips the water and the bilge plates work like the centre plate when heeled.

Suppose it depends on what you want to use her for, and where.

We have heard of several that have been fitted with non standard fin keels and apparently sail well, but so far no one has come forward with proper drawings of their conversions....

The weather helm problem is overcome by many, by the fitting of a small bowsprit, to spread the sail area and thus the centre of effort further forward...

hope this stimulates Senior owners to come forward, I will advertise the post on the Stoppress Page.

Regards,
John
Web site Coordinator

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Fiddler's Green
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Re: Ballast for Centreboard Senior

Postby Fiddler's Green » Sun February 8th, 2015, 11:16 am

Hi Martin,

I can see that the centre plate could be used to control weather helm, to an extent, by not lowering it a lot, just enough for it to be out of the slot. That would increase lateral resistance aft. As you lower it further its centre of resistance moves forward, thus would increase weather helm.

Be great if someone could try that theory out!

As for ballast, yes of course it helps to make her less tippy, but nothing like the effect of putting the same amount about 9 inches under the boat, as in the extended bilge keel option, the leverage is then greater of course.

So long as you treat her like a big dinghy you will be fine, they just need the movable crew as ballast! Can be very nippy! (but tender!)

Regards,
John
Last edited by Fiddler's Green on Sun February 22nd, 2015, 6:35 pm, edited 1 time in total.
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Martin Norris
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Re: Ballast for Centreboard Senior

Postby Martin Norris » Sun February 22nd, 2015, 4:54 pm

Hi again Bob and John,
Thanks for your comments.
I managed to get a bit of work done last week on my Senior building project.I have got the hog cut out and will very soon need to decide about the centreplate slot. Based on what I have read on Forum posts and your comments I am planning to increase the length of the centreplate by a foot and cast internal ballast at a later stage.On balance I am going for the large dinghy approach.

Any other observations would be appreciated at this stage,before I am fully committed.

Martin Norris

Bob Puzey
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Re: Ballast for Centreboard Senior

Postby Bob Puzey » Sat February 28th, 2015, 11:50 am

Hi Martin,

Glad to hear your build is progressing.
I'm definitely no expert on this as I didn't build my Senior. It was purchased with most of the build complete.
I think I would be reluctant for the centre plate housing to take up any more of the only open space inside the cabin.

Have you thought about adding a lead insert to the current centre plate design and encapsulating it? I don't know if this would work or not.

It would be good to hear the experiences of any existing centre plate Senior owners.

Bob Puzey

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Fiddler's Green
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Re: Ballast for Centreboard Senior

Postby Fiddler's Green » Sat February 28th, 2015, 12:30 pm

Years ago I repaired a 14ft heavy clinker dinghy for a friend.

His wooden centre board had a row of 3" round lead weights fixed into it along the lower forward edge. cannot recall how they were fixed, they almost appeared to be jammed in, maybe glued.

As the board was 3/4 thick these were not terribly heavy, but they did put the weight in the right place. also made sure the board went down! Something along those lines may be a good idea.

I have never heard of a centre board boat having real heavy weather helm.

I wonder if you Bob can recall if you had loads of, or any, weather helm when sailing with the centre board version you have?

I think the weather helm problem was one the stubby bilge keel version suffered from really. All the ones with bowsprits I have seen were on bilge keel versions.

For what it's worth.
Regards,
John
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Bob Puzey
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Re: Ballast for Centreboard Senior

Postby Bob Puzey » Mon March 2nd, 2015, 1:13 pm

I've not had any noticeable weather helm when sailing "Moonfleet".

To date I have only been out in very light winds, so not really pushing the rig or boat at all.
It think it would be unlikely that it would show under these conditions.
As I understand it weather helm is most pronounced when close hauled in stronger wind - is that correct?

Bob

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Re: Ballast for Centreboard Senior

Postby Eventide Owners Group » Mon March 2nd, 2015, 1:54 pm

Hello Bob,

Yes, after F3 as the boat begins to heel to the wind, when beating upwind, all the effects of hull shape, changed waterline shape due to heeling, centres of lateral resistance and centres of sail area come into play.

In my Eventide 26 ( 27'3" if Im honest, without the bowsprit...) at F3 one finger on the helm is enough to prevent it gently rounding into the wind.

At F4 a gentle hand grip, then you start reefing and if as I do you reef the main first, the boat is still gentle at F5, at F6 with triple reefed main and many rolls in the genoa it is managable but you have to be firm.

As I suspect most Seniors will not be out, hopefully in F6, seems owners have more sense, the Senior should sail in a similar way up to F4 and well reefed in a F5.

If a lot of weather helm is apparent at F3, then there is a problem to be cured. does not sound as if you have had that problem with your centreboard version, which fortifies my arguement that this was really only a problem in the shallow vbilge keel version, less in the extended bilge keel version, and with them a small bowsprit and moving the centre of effort forwards, cured it.

hope this helps the others.

Regards,
john
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