Hello. A few rigging questions for someone trying to learn

[Southbound]

Hello,

I am trying to re-rig and old 40 Foot 19,000 lb full keel sloop. I have a nice mast section but it is about 1 lb/ foot heavier than desired. The spar is 56 feet over all and weighs in at just under 5.9lb/ft vs. 4.8 that is desired so we're talking about a spar that weighs 61 pounds more than desired specifications. - fairly substantial amount.

However, The original spar in 1970 was the same approximate weight as the one I have been planning to put on. The original was also 5 feet shorter resulting in a pretty under rigged, slow in light air boat. So I suppose we are really talking about adding 30 lbs to the rig all of it above the original mast.

I am curious how much this extra weight aloft could potentially affect righting moment.

I am hopeful that I can compensate by using Colligos sythetic shrouds in part or whole to eliminate some of this.

I also intend to have the mast tapered to remove some of the weight high up. ...have good welders, engineers and machine shop working alongside me.

Does anyone have any thoughts on this or care to bounce around ideas with me?

Thanks in advance.

[Ian McColgin]

There's not really enough information here to do much more than guess. We don't know anything specific about the boat and no clue as to the original stability curve. A lot of designs don't have a very real or accurate set of stability calculations even at low heeling moments, much less to 110 degrees or more that's good if you really want off-shore happiness.

If the plan is to use the boat along shore, not venturing around the stormy capes and all, then just carrying on with the rig and then learning empirically what her heeling moments at least to somewhere past 45 degrees and calculating the rest to figure just where she goes to negative stability seems warrented.

After all, you've gone this far without predictive engineering. Might as well carry on and hope she can carry the sail. If she's really a heavy boat, the added weight aloft will only raise the center of mass a little and should not do much harm.

G'luck

[Southbound]

Ian,

I have more information I can share if anyone with some expertise cares to assist and discuss.

I have a sistership IMS certificate. I have information on the original sailplan as designed by Alden Yachts. I have had a spar manufacturer look at data and come back with a sail plan with their moments of inertia and section weight of 4.8 lb/ft.

I own a nice new mast that I can install. It will fit desired sailplan with minor modification. However as I stated it is a heavier by just over 1lb/ft than designed by aforementioned spar manufacturer. The design that I recieved was lighter than original (a good thing). The original spar was closer to the 6lb/ft.

The boat has a good stiff feel as it is but as mentioned underpowered in light air and actually suffers from Lee-helm. -not real common on CCA era boats in my experience. Granted part of that is because I think the main I had made was cut too flat and too much draft forward. -its dacron so that will change

Ideally a nice carbon fiber mast would be great. -not in the current budget.

So really I am wondering how much noticable weight could be removed aloft by sythetic rigging and should I be scared to add the weight of this replacement spar aloft.

Thanks,

[Brian Duff]

Now that I am safely removed from any expectation to know what I am talking about with boats, I am happy to throw a thought your way. (not a true goon rigger any more, just a broker)

Shifting weight aloft on your boat by 50lbs will make no damn difference at all.. You may notice if you are really really perceptive some difference in the pitching motion, heeling angle, or otherwise on the boat - but I bet not.

40' and 20000 is not particularly heavy, but I still feel that 50lbs used up at 1/lb a foot doesn't matter. You could remove something like 50lbs by changing to dyneema rigging if you are really concerned.

Tell us a lot more about the boat, a lot more, and your NAME - if you really want some help deciding on what to do.

Also, you might be so kind as to consider changing your username here, but that's just my vanity asking...