Adding Backstay & Uppers to Fractional Rig

[Terry Farrell]

I have a Precision 16 daysailer. It is a non-ballasted centerboarder (planing dinghy) with 400 lbs. displacement. Much like an Oday Daysailer.

It has the most simple of fractional standing rigs - a headstay and two side shrouds swept aft a bit (shrouds and headstay all attach to mast at same height). No backstay, nor turnbuckles or spreaders on stays. When sailing to windward in any significant wind, the headstay is like a wet noodle. I make the side shrouds as tight as I can (adjustable pin holes) when stepping the mast, but there is enough stretch in the wire and flex in the deck where the shrouds are attached that the headstay is completely untensioned. Also, without a backstay I have no way to shape the mainsail with the mast.

I'm thinking of adding a backstay so that I can bend the mast aft to flatten the mainsail when going to windward in a breeze as well as to be able to tension the headstay for a more straight luff on the jib.

Additionally, I wish to purchase a light-air headsail - something like a 3/4 oz. Doyle UPS that can sail to windward. I would be adding a bow sprit to place the tack 2 or 3 feet forward of the bow (and jib tack) and run the head 3 to 6 feet (masthead) above the point where the headstay attaches to the mast. The sail would be have a free-flying luff (no stay), but rather relies on the non-stretch rope sewn into the luff AND high halyard tension (2:1 purchase halyard seems to be the norm). I'm thinking that adding the backstay would also work wonders for this headsail. I wonder if it would also not be a bad idea to add small upper shrouds on spreaders to add side support to the mast - especially if I run the head of the headsail up to the masthead. This sail would not be used in more than 8 knots of wind sailing to windward, maybe 12 knots on a reach and maybe a couple more if sailing downwind.

Thoughts? Any suggestions on a good source of information on the ABCs of designing fractional standing rigging?

Thanks!

Terry Farrell
Tampa Bay, Florida

 

[gggGuest]

You really shouldn't need all that on a boat that small.
And if the boat is so floppy you can't get any rig tension on in the normal way I wonder what on earth a backstay is going to do to it?

Typically on a dinghy style rig you would use kicking strap (vang) tension and downhaul to bend the mast, depending on the mast. If its an untapered section then it all gets more difficult of course.

Do you have a wire luff in the current jib, and how much can you tension the jib halyard? In a boat that size its conventional for the jib luff wire/halyard to do the work of tensioning the rig and the forestay just to be there to keep the mast up when you take the jib down.

 

[michael pierzga]

Yes indeed. a Boom vang is sufficient for head stay tension .

Why make things complex.

 

[bregalad]

Ib 1981 I built a 25' sharpie that I designed with some input from Phil Bolger. It had a rig much like yours.

I had the same adjustments on the shrouds a you describe, but I had a turnbuckle on the headstay. That allowed considerable adjustment of tensions.

It had a large loose footed main with a sprit boom and a topping lift and snotter in lieu of the conventional gooseneck and boom. I only had three sails, a main and working jib made for the boat and a flat 'spinnaker' or baggy drifter of unknown origin that was given to me.

It all worked very well. I'd suggest shortening the headstay and using a turnbuckle to start. You nay fund that tightening things a bit and using a vang make enough difference that the other modifications aren't necessary.

 

[Gary Baigent]

If the hull is flexing, adding or having tensioning wires is not going to help; you need to stiffen the hull and deck.
However if you run two low "runners" from stern to say, half a metre up from deck to the shrouds, two part purchase system, hauling on the windward low runner, will really tighten your forestay. Although these are sort of runners, there is less clutter and windage.
Here is a shot of a much altered Piver Nugget tri with such a setup, works perfectly; the same principle will work on your monohull.

 

[Moggy]

I would have a look at improving the way that the chain-plates are attached to the boat/hull (are they?) and put some more adjustment in all stays Then you can assess how much of the issue is coming from the hull being too floppy. Maybe it is just the deck and the way that the chain-plates are secured. Maybe a bit of ply and glass could be used to tie the deck to the hull in a stiffer fashion? IMO there is no point loading it up too much if the strength isn't there to take it.

Edit: I just had a look at one, looks like a fully molded interior with difficult access!

Just as an aside, I once sailed a Hunter 30 that had THE floppiest mast I have ever sailed, nothing much would have helped that rig out in a blow! If the mast itself is a piece of spaghetti that may well be where the issue lies. I know many US builders use a lower temper alloy in their masts (T4?), that was the Hunters issue ---> cheap rig for "nice" conditions only.

 

[Moggy]

If it is the mast maybe a set of lowers and some adjustment in the side stays will largely sort it.

 

[messabout]

If your hull and mast is adequate, then Gary Bs solution is superbly clever and effective.

A long time ago,when I usued to race Windmills, the fastest boats used a floppy rig. We learned that a hiking crew could pull hard on the weather shroud and we could point higher due to the tensioned forestay. The tackle as suggested by Gary would have been illegal so we improvised by having the crew use padded gloves to handle the wire.

 

[Terry Farrell]

I would have a look at improving the way that the chain-plates are attached to the boat/hull (are they?) and put some more adjustment in all stays Then you can assess how much of the issue is coming from the hull being too floppy. Maybe it is just the deck and the way that the chain-plates are secured. Maybe a bit of ply and glass could be used to tie the deck to the hull in a stiffer fashion? IMO there is no point loading it up too much if the strength isn't there to take it.

Edit: I just had a look at one, looks like a fully molded interior with difficult access!

Just as an aside, I once sailed a Hunter 30 that had THE floppiest mast I have ever sailed, nothing much would have helped that rig out in a blow! If the mast itself is a piece of spaghetti that may well be where the issue lies. I know many US builders use a lower temper alloy in their masts (T4?), that was the Hunters issue ---> cheap rig for "nice" conditions only.

I'm quite sure much of the reason the headstay is so sloppy in a breeze is because of the way the chainplates are attached to the hull. I'm well aware of how a "proper" chainplate is generally attached - and that is not the case here. My hull-to-deck (i.e., molded interior) joint is an outboard horizontal overhang at "deck" level of about three inches or so. The "chainplates", such as they are, are through bolted through the middle of these overhangs - not into the vertical portion of the hull itself. I can apply pressure to the side shrouds and watch the overhang flex up and down. I did re-enforce the overhangs in the chainplate area with three-foot long stainless angles with the chainplates through-bolted through them. I only sailed the boat once after I did that and there was no wind - so I don't know how effective they will be. But if that is not effective enough, I can see that I need to get rid of whatever flex there still may be there.

Thanks for your input.

 

[Terry Farrell]

If the hull is flexing, adding or having tensioning wires is not going to help; you need to stiffen the hull and deck.
However if you run two low "runners" from stern to say, half a metre up from deck to the shrouds, two part purchase system, hauling on the windward low runner, will really tighten your forestay. Although these are sort of runners, there is less clutter and windage.
Here is a shot of a much altered Piver Nugget tri with such a setup, works perfectly; the same principle will work on your monohull.

Thanks for your input - that's a great idea. I had thought of some sort of simplistic running backstays in spite of all the evils I have heard about them. But your approach provides much of the same benefit with less of the problems. But as the next post suggests, I need to make sure my hull in the area of the chainplates is stiff enough to even benefit from being able to apply more tension to the side shrouds.

 

[Terry Farrell]

Ib 1981 I built a 25' sharpie that I designed with some input from Phil Bolger. It had a rig much like yours.

I had the same adjustments on the shrouds a you describe, but I had a turnbuckle on the headstay. That allowed considerable adjustment of tensions.

It had a large loose footed main with a sprit boom and a topping lift and snotter in lieu of the conventional gooseneck and boom. I only had three sails, a main and working jib made for the boat and a flat 'spinnaker' or baggy drifter of unknown origin that was given to me.

It all worked very well. I'd suggest shortening the headstay and using a turnbuckle to start. You nay fund that tightening things a bit and using a vang make enough difference that the other modifications aren't necessary.

Yes, I think you are correct. I have to have a way to snug the entire rig up tighter. I will add at least the turnbuckle to the headstay and do the other things that have been suggested. Thanks.

 

[Terry Farrell]

Thanks for all the suggestions. Pretty much all of them I think are spot on and I will be applying them. First thing is to make sure my side shroud chainplates are mounted securely to a solid part of the hull - i.e., minimize any hull/deck flexing in the chainplate area. Add a turnbuckle to the headstay (and perhaps the shrouds also). Maybe add the simple running backstay(ette)s suggested to both shrouds. And the great point of using the boom vang to tighten up the headstay. I have a boom vang, but I think the salesman at the marine store I bought it at sold me an undersized one. It's rather minimal and I have to really lean my whole body into it to really get any pressure on it - and the rope tears my hand up, etc. I'm going to go up a size so that I can really crank down on it. And I suppose just cranking down on the mainsheet would tension the headstay as well? anyway, great suggestions - all that should be tried before I go adding weight aloft in the form of more wires and fittings up at the top of the mast. Wonderful. Thanks!!!

PS: My sailing experience is moderate at best. I've had two sailboats previously - both fractional rigs but with upper and lowers on the sides, backstays and well-mounted chainplates. So I've never dealt with these concerns before. And I've never sailed on other boats. So all these concerns are new to me. I really appreciate the input. I'm quite sure it will help a good bit.

 

[Moggy]

In my experience most standard vang setups are not really up to the job. I found that a lever vangs did the job well, you can just add the required bits to your standard setup to really power it up.

http://www.flickr.com/photos/brichard/5713601717/

There are a few ways to skin that cat...

https://www.google.com.au/search?cl...4CQ&biw=1684&bih=927&sei=EK_NUL33OOSjige8rYAo

2c

 

[philSweet]

Terry, Which one do you have?

 

[Terry Farrell]

Terry, Which one do you have?

The one on the right. No wood in the seating area.

What do you have for me?