Stupid question? Fixed vs. swivel blocks

[nickspacek]

From a totally economical perspective, and if you don't already have the shackles kicking around, is there any other reason why you'd buy a (Harken examples) block with a fixed head vs. swivel?

I apologize if this is a stupid question.

[SEMIJim]

Originally Posted by nickspacek

From a totally economical perspective, and if you don't already have the shackles kicking around,

I don't understand what shackles have to do with anything.

Originally Posted by nickspacek

is there any other reason why you'd buy a (Harken examples) block with a fixed head vs. swivel?

Sometimes you need a block to swivel. Sometimes you don't. In some cases it's disadvantageous for a block to be able to swivel.

Are you looking for examples of each application?

Jim

[pdqaltair]

Originally Posted by SEMIJim

Sometimes you need a block to swivel. Sometimes you don't. In some cases it's disadvantageous for a block to be able to swivel.

Jim

Exactly. There are many times when a swivel will allow a tackle to twist and thus increase friction, while a fixed block will not. Some swivel blocks can add a locking mechanism, for this reason. For example, I have a swivel block on my mainsheet I've been meaning to swap.

[nickspacek]

Originally Posted by SEMIJim

I don't understand what shackles have to do with anything.

I'll probably say and ask lots of stupid things; I'm a total newbie. The boat I have doesn't have the tackle for the mainsheet, and I don't have a lot to go on to know how it was originally rigged.

I just assumed because the swivel came with a shackle and the fixed didn't, I'd need to buy one anyways to attach it to my boom. From the closest online store I've been using, the difference in price between the swivel and fixed means that it's cheaper to buy the swivel block (that comes with the shackle) instead of the slightly cheaper fixed block and shackle.

Originally Posted by pdqaltair

Exactly. There are many times when a swivel will allow a tackle to twist and thus increase friction, while a fixed block will not. Some swivel blocks can add a locking mechanism, for this reason. For example, I have a swivel block on my mainsheet I've been meaning to swap.

The question was driven by my cheap-ness, but I was also interested in other reasons for choosing one instead of the other. Since I am planning to buy two, one for mid and the other aft on the boom, it probably makes sense to get the fixed ones. The boom has two metal straps that can swing on the end of the boom, one for the block and the other for a deadend; at least, that's what I've been able to understand from the diagram I posted earlier: http://www.sailnet.com/forums/gear-m...ooter-p17.html

[SEMIJim]

Originally Posted by nickspacek

I just assumed because the swivel came with a shackle and the fixed didn't, I'd need to buy one anyways to attach it to my boom. From the closest online store I've been using, the difference in price between the swivel and fixed means that it's cheaper to buy the swivel block (that comes with the shackle) instead of the slightly cheaper fixed block and shackle.

The question was driven by my cheap-ness, ...

Not a good design criterion for choosing hardware, IMO Better way: Choose what you need, then try to fulfill that need as economically as possible, w/o compromising design/functionality/safety/usability/etc.

I don't know what you're going to require for your boom. On Abracadabra's mid-boom sheeting, which we upgraded to a 6:1 system, the Harken Carbo block on the boom is selectable: Fixed of swivel. Harken's applications notes, confirmed by Harken tech. support (as a result of a later conversation and design change), was to lock that block.

Since you don't know which you need, I'd try to get blocks that are selectable, and try each mode to see which runs more freely under all conditions. If I had to guess, tho, and this is purely a guess, my guess would be fixed.

Jim

[nickspacek]

Thanks for the advice! Part of my confusion has been that there aren't many Paceship P17s kicking around, and nobody's been able to conclusively identify the type of mainsheet rigging arrangement specified in the manual. I'm going to go with the selectable like you say, and when I've tried the various configurations I have in mind I'll be sure to let everyone else know what I discover!