Topic: Recommended weight of additional stuff?

I believe the official displacement of a CO26 is 5,800 lbs (though not sure if this includes mast, rigging, engine outboard in my case).  Looking for your thoughts on what the total maximum weight of extra stuff could be without significantly impacting safety and performance. 

Assume costal cruising conditions and the ability to distribute weight.

Re: Recommended weight of additional stuff?

I loaded mine up with a lot of stuff without noticeable change. Solar panel, self steering, 90L fuel, 160L water, food for 3 months cloths, charts and everything needed for a years voyage. I was surprised it even fit into the boat. The move from fresh to salt water helped.

Re: Recommended weight of additional stuff?

I bow to John's experience on this one.  No doubt you can load a lot on a Contessa.  I can easily stuff my car a couple of times over with all my junk.

The pamphlet for my 1976 JJ Taylor Contessa lists her displacement as 5400 lbs.  This is probably for a very empty boat!

I once read that the boot stripe on the JJ Taylor Contessas was set for salt water.  Because of the difference in water density, the boat sits deeper in fresh water.  Perhaps this is why my boot stripe is always partially immersed.  Having gone to the trouble of applying more than half a dozen coats of Interprotect to seal the bottom of my boat, it seems ridiculous to leave relatively porous gelcoat exposed to long-term immersion along the waterline.  On my boat the boot stripe is cream in colour, and hence is easily stained.  Therefore it is the most scrubbed area of my boat, and potentially the most worn area of gelcoat.  As you might guess, I have decided to raise the boot stripe this spring!

Now to and4ew's question:  The cockpit drains are about 4" above the waterline.  If you put a bunch of heavy people in the cockpit, the stern will depress, and water will begin backing up the drains onto the cockpit sole.  While this can be entertaining on a hot day with a merry crew, it poses great risk for the boat.  Most Contessa's suffer from poor seals on the cockpit sole panel over the engine compartment.  For my boat, if the drains back-flood then water will begin to pour into the engine compartment and the bilge.  Which moves water faster?  Two 1-1/2" drains fed by gravity, or a single 1-1/4" bilge pump outlet fed by a manual or small electric pump?  You can see how a couple of heavy rubber bungs might become very useful! 

Commercial ships are very interested in the figure TPI -- tonnes per inch immersion.  This tells the shipowner or captain how much cargo he can load for each inch the ship sits deeper in the water.  We can use this same idea to answer and4ew's question.

The waterplane coefficient is the the proportion of boat relative to the proportion of a box defined by length and breadth.  That is, Cwp = AREAwp / (LWL * BWL).  Unfortunately I've never seen this figure listed for the Contessa.  However we can make some reasonable assumptions and from there find the waterplane area (AREAwp).  (Sorry that I have not mastered subscripts on the forum!).

-- LWL for the Contessa is about 20ft.
-- BOA for the Contessa is 7.5 ft, so a reasonable guess at BWL is 7 ft.
-- If we look at the top view of the boat and estimate by eye the ratio of boat relative to the LWL and BWL box we might use a figure of 0.7.  Thus our AREAwp = 0.7 * 20 * 7 ==> about 100 square feet.  For this exercise we will neglect that the waterplane area changes as the boat sits deeper in the water.

Picture a slice of the boat taken at the waterline, one inch thick.  It would have a volume of 8.33 cubic feet (1/12 feet * 100 square feet).  A cubic foot of fresh water weighs 62.47lbs.  Therefore each inch you depress the Contessa corresponds to about 520 lbs.  For salt water one could use 64 lbs/ft3.  Therefore each each inch of immersion in salt water would correspond to about 533 lbs.  Personally I would use the fresh water figure as it is more conservative.

Now you can see where we are going -- by these estimates, if I put 2100 lbs into my boat (people, batteries, fuel, water, food, books, beach toys, etc.) then my cockpit drains begin to fill the boat and I am at risk of sinking. 

One other thing to consider might be to estimate the weight of water in the bilge, up to the cabin sole.  This would be the point at which you would be able to see that something was very wrong down below.  Until then the level of water in the bilge is invisible unless you lift a panel.  If your fully loaded boat can be filled to the cabin sole and not experience flooding from the cockpit drains then all is well.

As for weight distribution, if you can get the weight low in the boat, such as at the bottom of the bilge, then you can make the boat slightly stiffer -- it will heel a little less easily.  Put all the weight at above the deck and she becomes very tender and will try to flop around and shed all that deck cargo.  I encourage you to experiment with a bunch of people on a hot day!

This is not a bad exercise for sizing a trailer too.  Let's pretend that my boat is hauled out and put on a 1600 lb trailer.  For a dry empty boat weighing 5400 lbs the combination of trailer and boat weighs 7000lbs and could potentially be supported by two 3500lb axles.  However, my fully loaded boat might weigh as much as 7400lbs until I get all the tanks emptied.  This means that the axles of the trailer would need to be rated for an all-up weight of 9000 lbs.  Trailer axles are sold in steps so I would have to change from axles rated for 3500 lbs to axles rated for 5200 lbs.

4 (edited by bertinol 2017-02-26 15:17:54)

Re: Recommended weight of additional stuff?

Christopher...
Don't forget that JJT boats have a lighter keel - by 390 pounds - to compensate for the lower buoyancy of fresh water. This was done in about 1969 when Al Scott first brought the design over from England.

That means the bootstripe should be the same.
 
The sales brochure for JJT 352 - laid down 20 years later, at the end of the Canadian run - gives a keel weight of 2,300 pounds, and a total displacement of 5,400.

The early boats had a cast iron keel. Post 1980 - about boat 300 - the keels were made of lead, a heavier metal which took up less room allowing them to lower the floor.

The JJT boats have a longer cockpit, taller mast and the forestay is further forward to compensate for lighter winds and more sunshine in Canada.

5 (edited by MatildaCO26 2017-02-28 11:13:41)

Re: Recommended weight of additional stuff?

Christopher wrote:

Now to and4ew's question:  The cockpit drains are about 4" above the waterline.  If you put a bunch of heavy people in the cockpit, the stern will depress, and water will begin backing up the drains onto the cockpit sole.  While this can be entertaining on a hot day with a merry crew, it poses great risk for the boat.  Most Contessa's suffer from poor seals on the cockpit sole panel over the engine compartment.  For my boat, if the drains back-flood then water will begin to pour into the engine compartment and the bilge.  Which moves water faster?  Two 1-1/2" drains fed by gravity, or a single 1-1/4" bilge pump outlet fed by a manual or small electric pump?  You can see how a couple of heavy rubber bungs might become very useful!.

Hi and4ew and Christopher

What I am doing to my cockpit may be of some interest: beyondnorthhead.blogspot.co.nz

Hope to be finished and testing it out next summer--southern hemisphere summer that is.

Re: Recommended weight of additional stuff?

Thanks to Oliver for the corrections.  Nice to know the builders were more on the ball than we guessed!

It would be interesting to see the effect of the lead ballast on the stability of the boat.  Lead would have lowered the centre of gravity of the ballast which should have made the boat stiffer.  I wonder if the difference is noticeable.


MatildaCO26 -- bravo!  I admire that you have a vision for your boat and have set about making it a reality!

Re: Recommended weight of additional stuff?

Thanks Christopher for the thanks...

I've sailed in several Contessas of varying ages and I do think the later ones have a different 'feel'.  But I would have a very hard time explaining exactly what the difference is or saying which ones are 'better'.

Perhaps other members would be more articulate than me???????

Re: Recommended weight of additional stuff?

Christopher, thanks for the reply and the detailed support info.  Very enlightening (sorry for the pun) and comforting.

Re: Recommended weight of additional stuff?

And4ew, I had my JJ Taylor Contessa 26 "weighed" on haul-out last year... the crane operator claimed it was 5,000 lbs...  That is with all the stuff, minus the mast+shrouds+stays.

Honestly, there are Contessa's sailing around the world with 1 or 2 people on them and all their food, water, gear for a circumnavigation.  Unless you are taking it to THAT extreme, then I wouldn't worry.

More importantly is *where* the weight is stored.  Keep the weight out of the bow.  I find the Contessa tender, compared to modern boats, and therefore port/starboard balancing is a good idea as well.  i.e.  Don't put all your tools on starboard and all your pillows on port.

Regards,
J.

Re: Recommended weight of additional stuff?

My real weight issues are the outboard hung off the transom, not much I can do about that, and 10 years of accumulated tools and "just in case" junk I had stowed behind the companionway step.  I got rid of all that was useless (almost all of it).  And I will move the pillows.