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Old 17-11-2011, 20:51   #1
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Noobie Question

Kinda stupid question do yachts have a speed to never exceed like an airplane like I seen some cruise at 20 kts would it be safe to do say 40 kts if you can put enough power out
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Old 17-11-2011, 21:33   #2
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Re: Noobie question

Yes its called "hull speed" when talking about displacement hulls. If you find you are exceeding hull speed by any largish margin, it usually means something bad is either in the process of happening or about to happen.
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Old 18-11-2011, 08:32   #3
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Re: Noobie Question

Boats don't have max rated speeds attached to them, but they do have max horsepower for the engine (outboards), and inboards are sized properly by the manufacturer. As long as you don't equip it with an over-spec engine, no problems.
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Old 18-11-2011, 08:41   #4
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Re: Noobie Question

It's not a dumb question at all.

There is no official maximum horsepower above a length where a placard is not required. Naval architects for the most part will not design a boat with an unsafe amount of horsepower.

There is no law that a naval architect cannot design a 3000 horsepower offshore racer capable of traveling over 100 MPH where it is relatively easy to kill oneself.

For smaller boats, under 20 feet in length, there is a placard which lists the maximum allowable horsepower, maximum weight and maximum number or passengers. These maximums are calculated by a formula that is federal law to help keep people safe.
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Old 18-11-2011, 13:37   #5
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Re: Noobie Question

Depends on hull speed.
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Old 18-11-2011, 13:46   #6
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Re: Noobie Question

Can we go into some more detail about post #2? I got cold chills when I read it. Are we talking the dreaded death roll?
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Old 18-11-2011, 14:18   #7
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Re: Noobie Question

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Originally Posted by Matt sachs View Post
Can we go into some more detail about post #2? I got cold chills when I read it. Are we talking the dreaded death roll?
Actually when a displacement vessel exceeds its hull speed the Bow & Stern waves separate further apart and that vessel can end up burying its bow into the bow wave and sail under.
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Old 18-11-2011, 14:46   #8
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Re: Noobie Question

I assume foul weather and large swells are required to perform this manuver??
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Old 19-11-2011, 12:17   #9
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Re: Noobie Question

Matt,
You're talking about lots of sail up on a sailboat without a planing hull in very heavy weather situations. Not likely unless the captain is foolhardy.
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Old 19-11-2011, 12:25   #10
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Re: Noobie Question

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Kinda stupid question do yachts have a speed to never exceed like an airplane like I seen some cruise at 20 kts would it be safe to do say 40 kts if you can put enough power out
Haven't you ever seen Star Trek? When Kirk pushes the Enterprise too hard and everything's shaking and Scottie yells "She can't take anymore Captain!" That's what its like on my boat when we shoot through the narrows with the tide at 12 knots.
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Old 19-12-2011, 22:53   #11
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Re: Noobie Question

I'm guessing you're a pilot or know something about flying. The never exceed speed of an airplane is the speed beyond which structural damage to the airplane may occur. This can happen to any airplane no matter how large the engine, or even if it has no engine. A boats speed is limited by how much horsepower you put on it. If you put too much horsepower on a boat, you can break it. I've never seen a published "never exceed speed" for a boat as is published for aircraft, just maximum hp. That's not to say you can't break a boat with less than maximum horsepower. You have to consider the conditions as well. I've seen two boats with cracked hulls that had the rated horsepower or less. They were just run too hard for the conditions.
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