Here's one for the engineers/tinkerers!

Our boat has a round topped hoop. Looking at the mechanics of a flat top hoop, I wonder if it's possible to create the effect by adding two jambing cleats (about 20 cm from the top) - one on each side with a control line between them carrying the mainsheet blocks. This would enable the sheeting angle to be brought to windward.

Any thoughts?

Colin

You may be better using a split mainsheet, you will need a 4:1 mainsheet for this.  Instead of tying the end of the mainsheet to the block on the top of the hoop, if it is split about 2 foot from the end and the ends attached to the sides of the hoop then this will allow you to centralise the main.

The purpose of the square top hoop is to reduce the downward component of force on the boom whilst bringing it to the centreline.  The effect of what you are suggesting would mean that whilst you may be able to centre the boom your blocks would be so low that there would need to be a great deal of sheet force, thus closing the leach shut in all but the strongest blows when you would struggle to centre the main.
I had a similar system on 3389 where the previous owner had lowered the hoop and done as you are suggesting - it was crap.
Ring Winders, order a hoop and get yourself a length of track and a car - it makes a huge difference.

Theres a great diagram at http://www.merlinrocket.co.uk/gallery/view_photo.asp?folder=gallery/rigging_guide/mainsheet&file=traveller_controls.jpg. I'm in the process of restoring the hoop system to 3404 - the original round top hoop was removed at one time and replaced with a strop system that:

1. Offers little or no opportunity to "travel up" and centre the boom
2. Creates a lot of downward force on the boom when sheeted hard.
3. Is a pain with a long tiller extension and I always get in a mess with it when tacking.

One of the nice features is the release system for tacking that allows you to travel up on the new tack quickly without having to release the new leeward traveller line. Of course in a blow, you just leave it central - round hoop style.

Its been dead easy to set up, and my only dilemma is to get the hoop height right to cope with varying degrees of mast rake. Case of trial and error I think although the error part could be costly......

Cheers, John

Forgot to add that I was able to source a flat top hoop by placing a wanted thread on this site. Worth considering to keep the costs down.

What boat are you in, as this would also dictate the best solution to the problem?

The split mainsheet will also allow you to centreline the boom without extra downforce. You could also do away with the hoop and have the mainsheet start at the back and come forward along the boom to the thwart, which would allow you to remove the hoop and reduce the weight in the boat.

Stuart,

Thanks - we have an NSM2 (3387) - low bow tank, mast stepped at the tank top/centreboard case level. The rake is adjustable (from about 15 - 40cm) and fitted with aluminum spars and a strut.
The shrouds are adjustable (pulley system). There's a multi part purchase for the kicker (I haven't worked out the ratio yet!)
Obviously there's a round top hoop fitted.

We're just about to put her into the water (after a major re-paint/varnish lots of little jobs), so I'm now planning the options for the next re-fit...

At present any non-expensive options will be considered, but anything major will be next year....

Colin

Colin,

In considering your options you may want to review this article I did a couple of years ago for the magazine. Hoop v Strop. Follow link (if you are not a paid up MROA member,which i'm sure you are, you will need a password. 

Strop option very good. There are a number of people who swear by their use, to name a few Steve Leney, Dave Fowler and Laurie Smart. In fact unless the client requests Laurie builds his boats without hoops as it would appear to be a swear word in his yard!

If you decide to go down the strop route it might be worth dropping Laurie a line or give him a call, whilst the strop is a cheap option the set up is critical so he might be able to give you some advise/pointers, as i'm sure Dave and Steve would be happy to do as well.

All I would say is ditch the round hoop they are a complete waste of time.

Dear Richard,

I've read the article several times - it appears to be missing the "Figure 4" - centre strops....
Maybe this is to discourage the competition :-).

Seriously, though I take the point that the mainshhet should be used to control only the angle of the boom with the centreline - the kicker controls the rig bend (simplification!). I was wondering if I had enough width near the top of the hoop to improve things without major surgery....
I'm forbidden from removing the handle in the middle of the boat anyway....

Thanks to all,

Colin

Ah yes, I do now recall forgetting to insert a picture of Lauries old boat 3566 albeit I have loads of his and other boats on CD from my Mag editor days! Must give them to Mags!

Now thinking about it i'm sure the Wembley One Design (Simon Bagley) NSM2 had adjustable height round hoops. Dont know the numbers but I think Seveneye 3522,or there abouts, and Bald Eagle plus a brace of others had this adjustable height hoop system. Might be worth a call. The dinghy systems book I have at home for avid bimblers also has some good tips which I could scan and email to you if push comes to shove.

Several boats did have the adjustable height hoop including Seveneye and Bald Eagle, both were at Hampton for a bit though Seveneye modified to an aft mainsheet at one point.  The main drawback was keeping the hoop at the right height as mainsheet tension tended to pull it upwards & it still doesn't get the boom on the centreline.  Having thought from time to time about getting rid of my square hoop a few vigorous races on the sea have convinced me otherwise as it does provide good positive control and also a pushing off point to get over the side and something to hang on to in a wobbly gybe.  Also easy to grab all mainsheet purchases to swing boom over in same, not so easy with one of the split aft bridle arrangements.  After many years of using a long traveller even Patrick Blake now uses a square hoop, so like a lot of other systems, if the top sailors are using them you have to have a good reason for using something else.  The main reason for not having the square hoop is the fiddle of having to adjust it each tack, not so much of a problem on a 1 mile championship beat but a right pain on a river or short tacking down by Mill Bay.

I am having the same thoughts on Enchantment and came to the conclusion that the cheapest way to do this is to make a square top hoop from carbon tube with flat plates filletted in place. The top "beam" is a piece of solid carbon rod 10mm diameter, with a carbon block (the ones with a hole in the middle) forming the traveller. All carbon bits from carbonology.com

I'll let you all know wat it looks like.

Bald Eagle (NSM 2 / WOD) not only had an adustable height round hoop, you could lift the round hoop out an replace it with a square top hoop, the traveller rigging was all set up within the top section. Thus you had the ideal river boat option (round top) instantly convertible to an open water version.

What size of carbon tube are you going to use as I fancy giving this a go myself!

Vertical carbon tubes were 25mm OD and carbonology wrapped a couple of extra layers of matt around the outside as this is a little too small for my liking (I wanted their 29.8mm OD stuff, but they did not have any in stock). Using 2mm carbon plate for mounts to attach the tube to the thwart & centrecase knee & cleat bases. Epoxy fillet the plates in the right place (do this on the boat to get the orientation / angles right), then I was planning to wrap around the joint with carbon tow (like a lashing).

This sounds really interesting. Is there any chance you could post some photos please?

I will when I get round to finishing the project - my work has sent me to Italy for 2 months for training, so it is likely to be at around Christmas, but I'll keep the forum posted (not too many puns intended there).
Ciao

Andy - did you finish this project? If so could you post some details (and possibly photos) please?

Yep, square top hoop in carbon now made and hasn't broken yet - even with the lumps at Lyme Regis. I'll take some pics and send them to Mags in due course. I also converted to a one string system, which actually wasn't very difficult at all.

Enchantment will proudly be displaying her string and new rags at Camel Week prior to tackling the Nationals.

What about creating an add-on that converts a round hoop to a square one? Just a track and two stubby legs which bolt on.

Looking forward to Andy's photos anyway...