Would adding .5 metre to keel be worth it?

[minaret]

Originally Posted by HappyMdRSailor

Welcome to CF Foredeck!



Quoted before reading you NA buddy info posted later... But this is good stuff above here... I would honestly approach this backwards... Brion Toss is an incredibly nice guy, and has competent folk working with him... I'll bet for under $500, he can determine the maximum RM your current rig can handle...

Once you have that, you can slap on ballast, draft at whim... Not exceeding RM recommendations...



If this were my steel boat, I'd make and slap on a few slabs of lead myself... Actually... I'd weld a plate centerline under the keel, and through bolt the lead on both sides...



Another very good option...

Might be a money saver. The big advantage to going with Mars is that they do the math for you, no NA required. And since they make the majority of the ballast keels on the US market, they really know what they are doing.

However, the big downside is always shipping. Shipping a big lead torpedo costs as much or more than having it made. Therefore, DIY could be a big money saver.

[Stumble]

I am just speculating here... But a keel this size can fit into a 20' container at the Mars shop, and be loaded as standard cargo onto any ship headed to Europe. So shipping cost isn't going to be too bad. I would guess less than $1,000 to get it on the ship, another 2-3k for trans-Atlantic shipping, then another $1,000 to get it delivered.

Expensive sure, but not break the bank expensive. This is a 18,000lbs keel with about the same dollar value in virgin lead. On the flip side the keel you have contains about $9,000 of scrap lead value.


One thing that should be mentioned. Increasing RM isn't going to effect how the boat behaves at the dock very much. Ballast on starts to play a part as the boat heels, from 0-5 degrees the hull shape provides all most all of the resistance to roll, and that hull just doesn't have much initial stability. A deeper or heavier keel probably doesn't really play a part until at least 5 degrees.

[Sailor Doug]

If you can make a temple of a cross section area of your keel flame cutting is precise and quite inexpensive. A lot of metal fabricators sheet off fall (scrap) they could cut your keel plates from. Steel and scrap prices are extremely low right now. The more plates you use the more welding which will be the biggest cost. You could do it in stages at annual haul out.
If you are in a deep water area a deeper hollow keel would give you a bigger righting moment without increasing the displacement as much.


Sent from my iPad using Cruisers Sailing Forum

[unclemack]

Assuming the lines drawings & original calculations aren't available you can help your NA friend better to assess your boat with one photo taken from its centreline as far forward and one from as far astern as possible, using a longish lens for best perspective.
Camera needs to be held dead level to avoid convergence, about mid height gives closest approximation to drawing.

Depict stations/frames as accurately as possible on port side with, say, 2" white adhesive tape applied vertically from deck to keel/ centre line.
Off camera remote flash at night (shielded from lens) would be my approach.

The photo you posted should be enough to estimate CLR and sailplan CE.

Your estimate of distribution of tankage & other major weight will help as will your description of your boat's present characteristics.

Guessing at the end he'll say, "Yes, 4 or 500mm deeper will be about right. Try it and see"

I'd still wing it

[unclemack]

Oops, sorry about my last pointless post.

Should have re-read the thread first - then I might have spotted that you said in #7 that you do have the plans.

D'oh.

The whole time it's bothered me that a boat as tender as you describe would pass sea trials - only guess was that maybe the owner might have insisted on shoal draught & tall rig against the designer's advice and been embarrassed to do other than accept it as was.

If that had been the case though I thought it likely that the designer would have wanted to mark the alterations "unauthorised."

If not the case and a NA was solely responsible... wtf?

Hope you'll let us know how it goes

[HappyMdRSailor]

Originally Posted by minaret

Might be a money saver. The big advantage to going with Mars is that they do the math for you, no NA required. And since they make the majority of the ballast keels on the US market, they really know what they are doing.

However, the big downside is always shipping. Shipping a big lead torpedo costs as much or more than having it made. Therefore, DIY could be a big money saver.

A fact I totally neglected !!!

[barnakiel]

This is doable and will result in a stiffer boat. But you need a naval architect to draw the modification. Adding lateral area and lowering ballast may entail modifications to your rig.

b.

[Scout 30]

It sounds to me like you are more interested in increasing your initial stability rather than your ultimate stability. As was previously noted initial stability is more a function of hull design than ballast. Stability is not just about ballast but also buoyancy. Poor initial stability may be uncomfortable but it's not unsafe. I think the only way to increase your initial stability would be moveable water ballast. Lowering or increasing your keel ballast will increase your ultimate stability but you probably don't need that. A good book to read regarding this is Cruising Sailboat Kinetics by Danny Greene.

[minaret]

Originally Posted by Scout 30

It sounds to me like you are more interested in increasing your initial stability rather than your ultimate stability. As was previously noted initial stability is more a function of hull design than ballast. Stability is not just about ballast but also buoyancy. Poor initial stability may be uncomfortable but it's not unsafe. I think the only way to increase your initial stability would be moveable water ballast. Lowering or increasing your keel ballast will increase your ultimate stability but you probably don't need that. A good book to read regarding this is Cruising Sailboat Kinetics by Danny Greene.

Initial stability is also called form stability for a reason-adding ballast tankage will not change it either. The hull shape is what it is. I have made many form stability modifications by changing chine shape and/or adding sponsons to a hull-on large powerboats. Obviously not an option on a sailboat. He will have to live with his form stability as is.

[Scout 30]

Originally Posted by minaret

Initial stability is also called form stability for a reason-adding ballast tankage will not change it either. The hull shape is what it is. I have made many form stability modifications by changing chine shape and/or adding sponsons to a hull-on large powerboats. Obviously not an option on a sailboat. He will have to live with his form stability as is.

By moveable water ballast I was referring to water that could be pumped from one side to the other which would reduce the angle of heel when sailing. However, I believe it would actually reduce the boat's ultimate stability in a knock down. I think you're right that the boat is what it is & he'll have to live with it. Here's another thought: the hull appears to have a pretty low wetted surface which increases speed. Any increase in ballast would also increase the boat's wetted surface which would decrease it's speed. Simply lowering the ballast it already has would not have this effect.

[dagranger]

Your boat looks very interesting and more like a motorsailer very shallow draft I would bet it won't go to weather well. My guess is it was designed for motoring more than sailing..were I in your shoes I would defiintly hire a good naval architect to anaylize the hull and weights and come up with a plan that will fit your needs as to how you will use the boat..the boat is very large above the waterline and adding depth may work well. I know several friends who have done similar to adding more weight .5 meter may be too much or not enough..it is not cheap to add more keel good naval arch. might be the cheapest way to meet what you want

[RaymondR]

Slack bilges to minimize wetted surface and tall Bermuda rig tends to suggest a design for a light winds area?


I think if you are not careful you could outlay a fair bit of cash for not a big improvement in performance without enhancing the value greatly.

[brightontrader]

its quite a while since I looked at this thread and see quite few more useful comments, must have missed the email showing new responses, or gone to junk mail filter...sorry responders.

The boat does sail to windward surprisingly well as long as I remember I am cruising not racing keeping her fairly upright.

I looked again here as I am about to haul her out and am probably going to sand blast her off and copper coat, or I should say, re copper coat as there appears to be a dutch epoxy copper coat that is not very good already on her.

To do this I am going to move out of Brighton as the yearly fee has come around again and Premier don't seem to offer much in the way of flexibility to procrastinators who may or may not go south this year...or Scotland in my case...and am looking at yards in the Solent that allow sand blasting, and grinding steel, to get this and maybe the keel done too.

I had a friend over last weekend who had a 47 Swan copy that I crewed racing on in Puket years ago and was amazed when he told me that Quicksilver had a 1.8M draught, albeit a longer keel...we took line honours on the first day of the Kings Cup that year...

So a part of me tells me to sail her more, as is. The other part of me says "do everything at once while sh eis out and the hull is stripped clean". Its so hard these decisions, I suppose thats what these forums are for, to make it harder...

Thanks all, at least now I have a lot more to go on. (BTW, I do have a very worn image of line drawings showing the frames etcs, )