Altering the height of the wingdecks

[JoeWalling]

This is the next external task I've been thinking about. It is quite easy to do,by unbolting, shimming and rebolting the lower support brackets. Does anyone have any pro and con views? Thanks all.

Joe

[petrel]

Joe,

Firstly I do not have any answers either pro or con. Over the years I have given the idea some thought and could not find enough good reasons to do it. But this could be because of the sailing characteristics of my particular model Telstar.

When sailing in very light airs and at slow speeds both hulls tend to be in the water making for pleasant easy sailing but certainly not optimized for speed because of the drag from the three hulls. Yet, at higher winds and boat speeds the windward hull lifts clear of the water eliminating the drag from that hull resulting in great performance.

If you are looking for optimum performance IMHO there are two more critical issues:

1. Keeping the boat as light as possible - even empty is too heavy.
2. Keeping the hulls below the water line totally scum and barnacle free.

The difference between doing and not doing this is nothing short of remarkable. In my experience up to a factor of two in boat speed.

Geoffrey

[Ron]

Joe -

Just a comment, and it may not apply to your your particular modification. In general, adding shims or spacers between parts tends to increase the torque arm when the parts are under significant lateral stress, which will then increase the load on the fasteners and parts themselves. An inch or two may not matter that much, but there is a point where something can or will fail.

[Ron]

Sandy -

True, but the Corsair (and other) aka's and ama's were designed on the drawing board to be higher, without adding shims, spacers or anything else between the brackets, hull, amas and struts. I understood the question to be the effect of adding enough shims between these parts to significantly raise the struts. An inch or two would probably be OK, but something like 6 or more inches will introduce increased lateral forces to these parts that they may not have been designed to take. Picture the difference between a socket wrench with a 3 inch handle vs one with a 3 foot breaker bar. You won't break that many bolts with the small one while the big handle easily could. A much longer bolt and a number of spacers or shims in the middle would create the same effect.

I was thinking that he wanted to raise the entire aka or strut to get them further away from waves or chop, like the Corsairs and other tri's. Shimming just one of the brackets a drop to change the angle of the strut could work. But Tony intentionally designed them to allow all 3 hulls to be in the water at the same time.

[petrel]

If Tony designed the Telstar to have all three hulls in the water at all times why does that not happen with my boat as I wrote in my previous post?

Do all other Telstars sail with both outer hulls constantly in the water?

Geoffrey

[Ron]

I wouldn't say 3 hulls in the water ALL of the time. I won't fly a hull on my 28 in less than about 18 knots of wind on a beam reach. And that's with my somewhat larger (than the stock dacron) kevlar sails. Boat speed is approaching 16 knots at that point. But heavier or choppy seas could get one of the ama's out of the water. The older boats are somewhat heavier (for their size) and probably fitted with smaller sails so I'm not sure why you're doing it.

[JoeWalling]

Thanks for all your comments so far. Just to clarify my current thoughts - I'm (only half ) thinking about doing this for the least noble of reasons and that is - the look of the boat from dead forwards. This is my least favourite view of HUSH - I'm not sure the smaller windows work that well from this angle and I may change these anyway. Also the boat seems to 'toe-in' when viewed fron the front and the other tris have quite a pronounced and more attractive negative camber. However, I love the look of the boat from all other angles, including dead astern so I might just shim out the front. I know this will create a twist in the hulls so I was thinking of an inch at the absolute maximum. I understand that a small amount at the hinge creates a proportionately larger effect at the outer hull waterline - 3 or 4 to 1? What do you think about that idea?

I'm not concerned about more speed - HUSH is fast enough for me anyway - and I totally agree with the view on hull cleanliness and weight. Also, I don't particularly want the central hull to sit any lower in the water and I was thinking about extending the rear end of each of the outer hulls a bit, following the existing lines and just leading them backwards, as I did with the central hull - I think I could get another 6 to 9 inches. before running to a point.

What do you think of those ideas? This forum is great - we share so many ideas.

Joe

[Ron]

Joe -

A couple of negatives -

- By raising both of the ama's by about 3 or 4 inches, assuming that's what one inch gets you at the bracket, you will be shifting a significant portion of the overall weight to the main hull, and removing same from the ama's. The boat will be lower in the water with more draft.

- The boat will lose some of it's stability because the ama's will have less flotation. The boat will probably rock side to side somewhat as you walk around, even at rest. You could wind up with something like a Corsair which normally cannot have all 3 hulls in the water at the same time. They are almost always flying a hull.

I'm not sure what Tony had in his mind when he designed the older boats. The 28 was definitely crafted as a fast cruising trimaran. It can lift a hull, but it takes a fair amount of wind to do it. A Corsair F28 (closest of the Farrier boats in size) was built more for speed than comfort. Weight is at least 1,000 pounds less, aka's and ama's are both higher with less drag. I would have a definite problem catching a well sailed F28.

[ajaxpc]

I'm going to try this with Trina, because it isn't too expensive ...

My front cross braces are 35mm longer than the aft ones, so I'm going to get one set made 70 mm longer than the aft ones and swap front for back. This will add 35mm overall.

I'll need to make up some shims for the top brackets, but the angle will be small so I think possibly grinding some washers might do ...

In any case, it won't be to difficult to switch back if the result is unsatisfactory.

Things have been moving a bit slowly with the overall project - the boat is still in the yard, where it's been since October 2010. Parts are being made up in places, and progress is being made on details, but the overall effect is a bit depressing so far. Life's other unpredictabilities have interfered.

Alex.