Bendy Toy

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Question of the Week

Bendy Toy

Okay, our knowledge of ice boats and ice boating can be summed up like this: "That looks cool!" We know a lot of you are really into it, and we would be too if we didn't live in a part of the country that hardly ever has the temperature drop below 50 degrees, and if it does, we call it a state of emergency, request federal funds, and then hide in our McMansions until the winter temperature gets back to a hospitable 68. Whew.

So our question of the week is going to seem amazingly simple to you iceheads: Click on the pic of the DN's (again thanks to today's featured photographer, Dallas Johnson) and tell us why the rig falls to leeward in the middle of the mast section. Surely they could make a mast section stiff enough to prevent that. Maybe an intermediate shroud? Help a brother out.

01/17/08

bendy_toy.jpg

 

i.b

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It is to prevent sail twisting since it is too fast and twist would slow it down.

Question of the Week
Bendy Toy

Okay, our knowledge of ice boats and ice boating can be summed up like this: "That looks cool!" We know a lot of you are really into it, and we would be too if we didn't live in a part of the country that hardly ever has the temperature drop below 50 degrees, and if it does, we call it a state of emergency, request federal funds, and then hide in our McMansions until the winter temperature gets back to a hospitable 68. Whew.

So our question of the week is going to seem amazingly simple to you iceheads: Click on the pic of the DN's (again thanks to today's featured photographer, Dallas Johnson) and tell us why the rig falls to leeward in the middle of the mast section. Surely they could make a mast section stiff enough to prevent that. Maybe an intermediate shroud? Help a brother out.

01/17/08
 

Scowguy

Member
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At 60 mph, that sail needs to be FLAT. It looks weird, but the bending section sure seems to work. If you look at a DN mast section, you'd never guess the compression loading could bend the rigs like that. They're stout masts. The loads are pretty extreme.

 
The boys are spot on,

At these speeds you want a flat, lean and efficient sailplan for top speed. In the running start and acceleration a straight mast, full sail is needed.

This simple rig solution is close to the ultimate automatic rig that Frank Bethwaite aspires to deliver. When a gust hits you att top speed there is no time for manual depower and all weightmoves will slow you down. In the the perfectly tuned DN iceboat you just lay low in your lycra speed suit, grit your teeth and feel the acceleration.

The mast falling to leward has two components

1. Mast bend from compresstion for flat sailshape, twist control and lastly depower

2. Crossboard bend for pure depower, leaning the entire rig package to leeward in gusts. The bend comes from compresstion force from the mast through the mastbutt.

Now go out and try one

 
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Jim Shufflin

Member
65
1
Another advantage to the composite DN mast is that it allows the boat to absorb wind puffs that would have the old stiff Aluminum mast DN up on a hike near capsizing - very slow. With the bendy composite section, the puff is asborbed by the mast bend and boat stays relatively flat and under control.

 

[email protected]

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Another advantage to the composite DN mast is that it allows the boat to absorb wind puffs that would have the old stiff Aluminum mast DN up on a hike near capsizing - very slow. With the bendy composite section, the puff is asborbed by the mast bend and boat stays relatively flat and under control.
true; composite masts are just way faster as one just goes on when pressure comes...

 

Manfred

Anarchist
532
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North Germany
true; composite masts are just way faster as one just goes on when pressure comes...
Yes, all said here and above is right. But there is also a fine line between "how much bend do I need - and how much is too much". This guy from Russia does know about building these things but too much bend is slow...

Gummimast__R1_850_SA.jpg

 
Yes, the mast bend shown does reduce twist, but it also changes the sail's angle of attack in relation to the centerline of the boat. Dropping the middle of the mast to leeward also drops the leading edge allowing the boat to point higher.

 
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EGG

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It opens up the leach, and keeps you from tipping over. At 60 mph that is a good thing.

 

Todd Johnson

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Ask Jeff Kent of Composite Solutions (one of your advertisers). It was he that developed the concept and the technology to make it all work many years ago.

 

ILYAScow

Member
339
9
The only iceboating line you ever need to know. "The fastest I ever went was right before it broke". Be it a Nite, Renegade, Skeeter, DN, or sternsteerer.

 

GTim

Anarchist
605
6
Erie, PA
Especially in lighter winds, when you are taking off, slowly sheeting down harder and harder and then, when the mast bows out to leeward....zoom. It's like the turbo charger kicks in. It's scary to watch it bow out during big gusts....you swear it's gonna explode. :ph34r:

It's a totally insane feeling to be ripping around in even the slightest of breezes.

Temps are going to be low enough here to get some ice going.....time to get mine out of the garage rafters and sharpen up the blades!

 

tprice

Anarchist
618
1
Chesapeake
Yes, the mast bend shown does reduce twist, but it also changes the sail's angle of attack in relation to the centerline of the boat. Dropping the middle of the mast to leeward also drops the leading edge allowing the boat to point higher.
What he said!

Just like why a Soling sags it's jib so much. Displacing the headstay (leading edge) to leeward allows the boat (hull) to point relatively higher. (It's not all to gain fullness in the jib) Works great in flat water where you can put your foils at fine angles to the flow. Iceboating certainly counts as flat water!

In certain conditions, if the rules allowed it, having your forestay on a track, allowing it to slide to leeward could be a good thing. (and structurally and complexity wise a bad thing) Interestingly, the Racing Rules knew this many many years ago and shifting forestays have been specifically written out practically since there have been rules.

188foto.jpg

 
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