[Public-List] rigging

Mon Jan 18 07:39:24 PST 2010

Good morning Don - Sorry I couldn't make it to the meeting.

Be careful with the Harken catalogue when using it as a text for  
strengths... that company is notorious for phrasing specifications in  
a manner that can lead one assume an over estimated level of  
performance (blocks and winch powers in particular)

Gord

On 18-Jan-10, at 10:16 AM, Don Campbell wrote:

>
>   There has been an extensive discussion on mast beams and rigging  
> and the pros and cons of various rigging systems. The over-riding  
> consideration in any refit is safety and it is never the safety of  
> the conditions that one decides to sail out of port in,  but the  
> conditions that one gets caught in while out that usually determine  
> the maximum loading that we put our boats under. It has been shown  
> many times that boats will take more than people in most of these  
> circumstances so whatever the designer has done to make boats so  
> they will weather a storm, they have done a fairly good job.  
> However, they have done this using design principles which involve  
> numbers and algorithms that dictate working load limits (WLL) and  
> breaking load limits. Usually, we do not have those numbers at hand  
> when we make decisions to repair or replace. The best we can do is  
> look at materials for sale that seem to match what is there. We can  
> also use recommended safety factors of 5x for loads not having to do  
> with lifting people and 10x load if we are lifting people. That sets  
> breaking loads at 5 x the WWL (so if you tension the rigging to 1000  
> lbs, you will need 5000 lb wire to be at that safety factor) and  
> somewhere around 2500lbs if we are lifting people. Oversizing line  
> is never a problem but it will put the breaking point of the system  
> on whatever the next weakest link is.(chainplate bolts?)
>   As an example problem of choices, the Harken catalogue gives  
> measurements of breaking strengths of three 1/4" SS 1-19 wires: 302  
> is 8200 lbs, 316 dyform is 8844 lbs and 316 is 7090 lbs. I suggest  
> that not many of us could tell the difference by looking at these  
> three wire ropes and I have a suspicion that there are few of us who  
> could say what Whitby originally put on our boat or what is on our  
> boat now if we have replaced the rigging..
>   I have taught the ropes and knots materials for the Canadian Power  
> and Sail course for a number of years and what I tell my students  
> every time is to know what you need and know what you are buying by  
> manufacturers specifications given on the materials that you buy. If  
> there are no specs given on the roll of rope, then you don't know if  
> the roll of rope is first grade or seconds. Knowing what you need is  
> not just 1/4" wire rope. It is what spec on 1/4" wire rope you feel  
> will be safe ( I'm not a lawyer) for the worst conditions you will  
> ever be out in and then will that provide the WLL or breaking  
> strength that the designer has given in his drawings.
>   I never rely on price to tell me what the value is of the product.  
> Most often we get what we pay for. There are many times I have gone  
> to commercial riggers - the people who do the rigging for cranes and  
> commercial lifting devices - for wire rope because they always have  
> the specs and usually do not price things with BOAT in mind. That  
> way, I know what I am getting when I buy wire rope from them..
>   Therefore the questions that I would ask you to sort out are do  
> you know the design requirements for the products you are fixing or  
> replacing? and  does the product you are making or buying meet those  
> specifications? If the answer for the second is that you don't know  
> or that that product does not measure up to design requirement,  my  
> recommendation is DON"T BUY IT!
>   We have been given 2 figures on rigging in this recent discussion,  
> $1000, from a source in Florida and $2000 from others. What we don't  
> know is whether  both  rigging purchases contain the same components  
> for a start. If one is done with Nico press fitting and the other  
> with Norsemen fittings, there is one difference. If turnbuckles were  
> replaced in one but not the other is another significant difference.  
> Make sure you know what comparative pricing does for you, and if you  
> do go for a group purchase, make sure you get a well described spec  
> list before you tender it. That way, your comparative pricing will  
> be effective.
>
> Don #528 and #469
>
> Jonathan Adams wrote:
>> All,
>>
>> Mike and I have been communicating regarding a group buy of rigging  
>> material either fabricated or just the materials. If there are  
>> folks interested in participating in this, let me know.
>>
>> Also note that Gordon Laco has rigging material at great prices for  
>> A30 members - I got my turnbuckles through him.
>>
>> Jonathan
>>
>>
>>
>>
>> ________________________________
>> From: Richard Cronk <manan at nb.sympatico.ca>
>> To: Public-List at lists.alberg30.org
>> Sent: Mon, January 18, 2010 7:15:19 AM
>> Subject: [Public-List] rigging
>>
>> Try Mac sails in Fla for rigging ..Got mine there and was  1/4  
>> inch  with fitting  ..less than 1000;00
>> D
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