Author Topic: Ventral fin in 14ft sup  (Read 7475 times)

tarquin

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Ventral fin in 14ft sup
« on: November 03, 2019, 02:20:52 AM »
Thinking about putting one of these in as a ventrall fin. If its retractable you can just put it away in calm conditions.
 What are peoples thoughts of the pros and cons of a ventral fin.
 The whole unit weighs just over 600 grams. I would cut the fin down as it is 14 inches. A little extra weight to reinforce the area. Is adding 600-700 grams worth the added stability and better tracking in rough conditions.

TallDude

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Re: Ventral fin in 14ft sup
« Reply #1 on: November 03, 2019, 07:24:13 AM »
I think they work great when you need them. I've paddled a board with one and it tracked so well. In side wind or quartered wind it worked just like a dagger board when on a tack. I wouldn't want it surfing or probably down winding either.

tarquin

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Re: Ventral fin in 14ft sup
« Reply #2 on: November 03, 2019, 08:07:37 AM »

 The fin is 14 inches so I can cut it right down. The actual fin weighs 300 grams. If I put the control near my foot I can raise or lower it as needed.
 Most reports I've seen people like them but they cause problems in certain conditions so its 50/50.

Luc Benac

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Re: Ventral fin in 14ft sup
« Reply #3 on: November 03, 2019, 08:18:14 AM »
They make a lot of sense for touring. They help a board that has a tendency for the nose to be blown in side wind.
I do not like to have things on my boards and rather keep simple and to a minimum. So i would compare the weight of a normal fin box installed and a LA ventral against your apparatus.
Then it is simply a question of putting the click-it fin on when you are doing distance or leave it out when you are downwinding.
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PonoBill

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Re: Ventral fin in 14ft sup
« Reply #4 on: November 05, 2019, 08:28:18 AM »
Looks like you double posted this. Here's my answer I posted there with some additions. Mark Raaphorst designed a really nice retractable ventral fin that could be controlled by pushing a level with the paddle. He abandoned it after a lot of testing.

It's too big. All you need up front is a little fin, and often you won't need that. It needs to be in exactly the right place though. If you have any nose rocker make sure it's behind that, having the fin come in and out of the water while you're steering in chop is a great way to get tossed off the board. I found my Blackfish was a little faster with a very small, very thin ventral fin, but the compromised control wasn't worth the speed difference. The only place I found a ventral fin to be really worthwhile is going upwind, and even then, small is good. I made mine out of aluminum and they were only about three inches long and an inch high. Half the size of Larry's smallest ventral at the time--I've seen some smaller ones from him since then.

I also made a self-steering front fin that was retractable and steered with a wind vane to make going up or cross-wind much easier. It worked great until the rider turned downwind, and then even a monkey would have been tossed off the board. These days i keep it simple.
« Last Edit: November 05, 2019, 08:31:18 AM by PonoBill »
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tarquin

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Re: Ventral fin in 14ft sup
« Reply #5 on: November 05, 2019, 12:12:10 PM »
Thanks for the replies. Think I will forget about it. Sounds easy to get it wrong. Already designed my own board so leave it at that.