Adding ballast or something like it?

[scottorious]

I have a cal 34. The later model cal 34 shows that it has 900 pounds more ballast in the same hull design. Not that I want to add 900 pounds but would adding anything (integral water tank, batteries, chain storage) be wise? The bilge on my boat is just massive. So moving the heavy stuff down there would be nice. Anybody advise against it? Or adding a some weight in the form of a half lead teardrop onto both sides of the keel. Maybe just 100 pounds per side at the bottom of the keel. Has that been done? Could it just be Encapsulated in fiberglass and epoxy and fiberglassed to the boat?

[Stumble]

Yes it could be done, but what are you trying to achieve? It's possible the latter boats had a shorter keel and thus need the extra weight to get the same RM. Or that they changed the hull design a bit that removed static RM so added weight to get it back.

If you are going to add weight then adding a bulb is far more effective than internal ballast, but frankly bolt on additions have a poor track record. It's a lot of extra wetted surface for minimal gain in most cases. If you really want to change the performance of the boat with a keel job it would really be advisable to just buy a new high aspect keel with a bulb. Longer span, for the same weight, and the reduces size of the keel itself keeps wetted surface area about the same if not lower. But it's an expensive undertaking.

[psk125]

Have to agree with Stumble on the idea of adding wetted surface. You can add weight pretty easily by putting lead ingots (or whatever) into the existing bilge. It won't be as low down as it might be, but may get you improved motion or whatever it is you seek. Before doing this, however, think about why you want the added weight. Are you overly tender now? Perhaps Cal was looking to increase sales in SFO and added the 900 more pounds to make the boat stiffer in the heavier conditions there. If you're not over on your ear so much now, perhaps you don't need the adtl weight.

[GordMay]

➥ https://marskeel.com/production/repa...ability-bulbs/

➥ https://marskeel.com/production/repa...ft-reductions/

[TrentePieds]

As Stumble asks - what's impelling you to do such a thing?

There is no reason at all for an owner/user to concern himself with the absolute weight of ballast. Absolute weight of ballast is chosen by the designer when he considers important conflicting metrics such as Righting Moment and Period of Roll which are design parameters that speak to stability. Upon consideration of hull form ("lines") the designer chooses that weight of ballast that will give him such values for those parameters as empirical evidence, his own and that learned from other designers, tells hims will result in the best compromises for traits such as stability and sea-kindliness.

No reason you shouldn't mess with the designers experience-based decisions if that is what you'd like to do. But there is no need for it, and it is unlikely that you, unless you are a naval architect, could effect improvements.

TrentePieds

[toddster8]

On the other hand, if the factory decided to add 900 lbs mid-way through the production run, there was probably a reason for it. Might be worthwhile to find out where they added it at the factory.

[Suijin]

Unless the boat is crazy tender there's no point in adding more ballast just because later iterations had it. As mentioned there were probably other design changes that led to that change. You'll just be slowing the boat by gratuitously adding more weight.

Aside from that, if you add any heavy equipment to the boat, it goes without saying that the lower down and closer to the center of the boat you can put it, the better.

[Cadence]

Stumble summed it up. And the designer had his reasons.
Put anything heavy in the bilge you want but don't mess with the design.

[rhubstuff]

If you want to try this out, put a whole bunch of plastic water jugs in the bilge and go for a sail on a nice day. If you like the result, there are lots of options to add more permanent weights. My guess is that you won't notice any difference. The designer was probably right in the first place.

[TrentePieds]

Yep. The boat is a Bill Lapworth design. IMO it's a brave man that second-guesses Bill Lapworth :-)!

TrentePieds

[scottorious]

I'm not second guessing him at all. Just makingredients an observation that when the cal 34 was past its days of racing it was turned into more of a cruising platform. The hull design stayed the same(including keel design and draft) but the sail area went down and the ballast went up. So I'm not second guessing anyone but maybe thinking as a boat intended for cruising he (Lapworth) thought it could use some more ballast so I'm thinking the same. I'm thinking more along the lines of finding a way to store anything heavy in the bilge. Chains, batteries and water.

[TrentePieds]

Yes, that's good. "Cargo" should be stowed low for many reasons. 900lbs is the weight of four well grown men, or about twice the weight of your engine, i.e. more than a triviality in a small boat. But, as always, we are working with compromises. Boats should be kept as LIGHT as possible for many reasons and wetted surface should, for many reasons, be kept as little as other design considerations will allow.

Just for your own interest, run the numbers for "pounds to immerse an inch". You'll find that in that respect 900lbs won't settle 'er much. Run the numbers on where the Centre of Gravity will lie if you stick a 900lb lump of lead in the deepest part of your bilge, and you'll find the the downward shift of the CG might be an inch or two. So, ceteris paribus in terms of the rig, what will you gain in terms of stability? For interest's sake, 900 lbs of lead is a lump about 14"x14"x14", but don't forget that you can't lift that! If you are gonna do it, make sure that you make up the total weight in "pigs" that you have the strength to shift about while you are belly down and contorted on the cabin sole, and that you have adequate means of securing the pigs in the bilge in case you take a knock-down!

Now, keeping your ground tackle low in the bilge makes sense in terms of observing the basic rule, but you'll pay for it in terms of handiness. TrentePieds has her chain locker just above the waterline right at the stem. Brings her down by the head by an inch, but bringing the chain midships to the bilge just isn't worth the hassle for my kinda sailing.

I think you are making more of this than it warrants. I bet you that in her present state the boat isn't giving you any grief at all. Just go sailing and be happy :-)

TrentePieds.

[UNCIVILIZED]

To play Devil's Advocate on this. If the boat is now in day sailing, & cruising mode, then 4-8 bodies are now gone missing from the windward rail 24/7. Which that much mass translates into more RM than an extra 900lbs in the keel. And it's also a lot more weight for the boat to carry around than some extra keel lead. So it can't hurt to try it out & see. The boat surely won't be overloaded by adding 1/2t deep in her bilges, & the regained RM could be of great benefit. Especially as with Cal 34's the boom was shortened once or twice over the years in efforts to dial out some weather helm. And extra ballast/RM typically helps with ill mannered tillers.

The 1st gen Cal 34's displace 9,500lbs, with 3,750lbs of ballast. And their J=13.75', with an E=14'
The MK III Cal 34' displace 10,200lbs, with 4,650lbs of ballast. And their J=13.75', with an E=11' With the MK III also sporting a 2.25' taller rig. Though given that the boats were built in SoCal, I'd not at all be surprised if a few sport rigs yet taller than this.

So by the numbers, cropping the boom by 3' seems an obvious attempt by the factory to shed some weather helm. And boats of this era are kind of notorious for having non-miniscule amounts of it to begin with. Which ballast will likely help with. And the hull form of the boat is such that they take a bit of extra weight fairly gracefully, while only sinking a bit more than an 1" deeper into the water.

My proclivity for turboing boats aside, I say go buy some scrap metal, & fill the deepest parts of the bilge for a few test sails. And if you like the change, then add some weight down low in the proper manner.

As a comparison. A Ranger 33', a boat of the same era, built by the same folks, weighs 10,500lbs, & has 4,500lbs of ballast. With both the J, & E being 13.8'
Ranger 33's have a huge bilge sump at the aft end of the keel, & at times is surely was tempting to add 1/4t - 1/2t to it. Not that they're ill mannered, far from it. But regaining RM lost by a rail absent crew would have been much welcomed. So adding ballast to the more svelte of the Cal 34’s shouldn’t hurt her (much), & it may in fact help.

Note: If you double wrap the sacks in plastic to keep them dry, you might simply snag a dozen bags of cement from Home Depot. They're all of a couple of dollars/per. That, or sand. So that your experimental ballast truly is fairly low. Though not so much so as lead, or lead mixed with resin.

[Cheechako]

Through bolt 44 lb zincs either side of the keel base? (is your cal a bolt on lead keel?) I like the half round or teardrop lead idea to the bottom of the keel. Down there a lot less weight to add than in the bilge.
But do you feel the boat is too tender now? IF not, fuggitaboutit

[TrentePieds]

Miss Google, the all-knowing, informs me that right from early days the C34 came in standard and shoal draft versions. The standard was 5'7 and the shoal was 4'8". In other words the original 5,000 lbs of ballast was moved UP 11". Without actually doing the numbers, I would think that the EXTRA 850 lbs Miss Google sez the shoal draft version carried in this new, higher position was just nicely the Lapworth determined quantity required to retain the MOMENT as it was intended to be, given that the new MOMENT ARM was now a bit on the stumpy side.

OP hasn't told us what his draft is, but if his boat is full draft, there is no need for the extra ballast. It's possible, but we don't know this, that the OP has stumbled over specs for the shoal draft version without realizing that that is what it was.

TrentePieds