Hobie 16

General Sailing Discussion
Bill Roberts
Expert
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Joined: November 17th, 2003, 9:13 pm
Location: Stuart, Florida

Re: Hobie 16

Post by Bill Roberts »

Want to soup up a H16? Put SC rudders on it. This will make the Hobie sail faster to windward and tack much better.

J Drew
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Joined: September 9th, 2013, 12:39 am
Boat Make/Model: SC 20
Location: n. florida

Re: Hobie 16

Post by J Drew »

Ok, I'll bite, what's the difference in the two rudders and why will it change things?

Bill Roberts
Expert
Posts: 515
Joined: November 17th, 2003, 9:13 pm
Location: Stuart, Florida

Re: Hobie 16

Post by Bill Roberts »

The H16 is crying for larger rudders, rudders with more area. A H16 set up for racing leans the rig as far back as possible. This puts some of the sail side force on the rudder. The rudder makes much less drag for a given amount of side force than the H16 hull does. Therefore the boat will go faster to windward with more side force from the sails being carried by the rudders. This means the hull has to carry less side force from the sails. A bigger rudder can carry more side force. Ever heard of SHARED LIFT? A H16 with the rig leaned well aft is "SHARED LIFT" in action.

Also remember that the H16 hull shape presented to the water at hull waterline is an airfoil in reverse. This is the hull shape
that is attempting to generate side force equal and opposite to the sail side force, an airfoil flying backwards.

J Drew
Professional
Posts: 104
Joined: September 9th, 2013, 12:39 am
Boat Make/Model: SC 20
Location: n. florida

Re: Hobie 16

Post by J Drew »

Shared lift
From what you have explained, shared lift will be more evident on a h16 with larger rudders. In raking the mast back to balance the center of effort between the two points of side force
Last edited by J Drew on August 4th, 2016, 12:35 pm, edited 2 times in total.

Bill Roberts
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Joined: November 17th, 2003, 9:13 pm
Location: Stuart, Florida

Re: Hobie 16

Post by Bill Roberts »

Drew,
The highly raked aft mast/rig on a H16 is something that already exists today and has for years. The H16 is faster with the rig raked aft because it takes some of the lift force off of the hull and puts it on the rudder. H16 sailors learned this by trial and error a long time ago. The rudder makes less drag than the hull carrying this delta amount of side force. A little less drag makes the boat a little faster.
If we assume the H16 hull acts like an airfoil, then the resultant side force acts at 40% of the length. We have to remember that a H16 asymmetric hull shape is an airfoil flying backwards, sharp trailing edge going forward, pointy edge forward. Max hull width or foil thickness is back under the tramp at about 2/3rds hull length measured from the bow. Who knows where the resultant side force acts on a H16 hull, somewhere between the bow and the stern.
So, tuned up racing Hobies already have the rigs raked aft to the max, so do Hobie Waves etc and they didn't come from the factory that way. Anyway, as tuned today, the H16 rudders are highly loaded. They stall very easily. A much larger rudder would really help a H16 sail much better. The largest readily available beach cat rudder is a SC17 rudder.

Kevin Keller
Professional
Posts: 338
Joined: September 24th, 2006, 2:56 am
Boat Make/Model: SC-20, ARC22
Location: Honolulu

Re: Hobie 16

Post by Kevin Keller »

Thanks Bill. Even though many of us do not comment we all enjoy reading about your wealth of knowledge.

Bill Roberts
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Joined: November 17th, 2003, 9:13 pm
Location: Stuart, Florida

Re: Hobie 16

Post by Bill Roberts »

Thanks Kevin. Stay tuned for something that is going to knock everybody's socks off.

Kevin Keller
Professional
Posts: 338
Joined: September 24th, 2006, 2:56 am
Boat Make/Model: SC-20, ARC22
Location: Honolulu

Re: Hobie 16

Post by Kevin Keller »

Bill,

Standing by!

I was just visiting in Naples and Boca Raton. I was wondering if you lived near and wanted to go sailing.

Kevin

Bill Roberts
Expert
Posts: 515
Joined: November 17th, 2003, 9:13 pm
Location: Stuart, Florida

Re: Hobie 16

Post by Bill Roberts »

Kevin,
I live about 50 miles north of Boca. I live on the St Lucy River and that is whee I sail mostly. Right now the St Lucy is full of toxins from Lake Okeechobee. The public is advised to stay off the river. For the past month I see no sailboats or power boats using the river. This is a bad situation and I may have to move my boats to another location to sail.

What boat do you sail? Maybe the ocean is the best place to sail around here. There is a large fresh water lake in West Palm Beach.

Laz
Devloping
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Joined: September 20th, 2010, 11:21 am
Boat Make/Model: SuperCat 15

Re: Hobie 16

Post by Laz »

Charlotte Harbor? The Peace River? Good wind and protected seas.
"Sonja" - SC15, Havre de Grace MD (top of the Chesapeake).

Bill Roberts
Expert
Posts: 515
Joined: November 17th, 2003, 9:13 pm
Location: Stuart, Florida

Re: Hobie 16

Post by Bill Roberts »

Are these places on the east coast of Florida? Near what town ?
What SIZE, CLASS, TYPE of boat do you have?

Laz
Devloping
Posts: 21
Joined: September 20th, 2010, 11:21 am
Boat Make/Model: SuperCat 15

Re: Hobie 16

Post by Laz »

Oops, I got confused by the reference to Naples. Never mind. I'm up here at the top of the Chesapeake on my SC15.

You want to chat with Kevin. Apologies for being nosey.
"Sonja" - SC15, Havre de Grace MD (top of the Chesapeake).

Kevin Keller
Professional
Posts: 338
Joined: September 24th, 2006, 2:56 am
Boat Make/Model: SC-20, ARC22
Location: Honolulu

Re: Hobie 16

Post by Kevin Keller »

Bill,

We have emailed in the past. I live in Oahu. I own a SC20 I restored and just picked up a ARC22. It's been too windy for the ARC22 lately. I have only sailed it twice since bringing it over a couple of months ago.

Kevin

Bill Roberts
Expert
Posts: 515
Joined: November 17th, 2003, 9:13 pm
Location: Stuart, Florida

Re: Hobie 16

Post by Bill Roberts »

Kevin,
The 22 is designed for light winds. It has the SC20 tall rig sail plan for light winds. When we race the 22, we have some sails that are 30% reduced in area, main and jib. There is nothing slower than being overpowered in strong winds. The sail area that you can't drive , has little to no angle of attack on it because you can't hold the boat down, is creating aerodynamic drag. That drag subtracts from the forward thrust that the driven part of the sail area is developing. If there are white caps, 15 or more, we use the smaller sails and go faster than we could with the full size sails. The top speed of the boat, any boat, will happen with smaller than the standard size sails for that class boat.
THE WINDSURFERS reach speeds of 50 tom 60 mph with very small sails, like half or one third the area of a sail made for 10 to 12 mph winds.
Boats sail on 'RELATIVE WIND SPEED. This is the vector sum of true wind speed plus boat speed. You can go out in a 15 mph breeze and have 25 to 30 mph wind blowing through the sails. This is why you have to cut the sail area back in winds over 15 mph because your boat will develop so much relative wind speed. Slow catamarans won't do this. They don't know what you are talking about. The Am Cup boats will triple the true wind speed. They can go out in 15 mph winds and have 45 mph wind blowing across the deck and they are going 30 mph. They go downwind and the sails are trimmed for a close reach because the relative wind is so far forward. Your boat will do this same sort of thing just not to the degree that an AM Cup boat can do it. Your boat will sail 150 degrees downwind with the flat chute with the relative wind forward of abeam and flying a hull and you will be going smoking fast looking back at the white caps following you.

PS In 20 mph winds we need a SC20 rig and small sails and we would go still faster.

Kevin Keller
Professional
Posts: 338
Joined: September 24th, 2006, 2:56 am
Boat Make/Model: SC-20, ARC22
Location: Honolulu

Re: Hobie 16

Post by Kevin Keller »

Bill,

I should try my SC20 SR sail on it. Maybe I will get one of the those halyard extenders.

BTW how big of a sea anchor would you use on the 22 for righting?

Kevin

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