# J-203 hull speed

anyone know the hull speed of a wenonah J-203? what about the J-200? thanks.

For any displacement boat…

– Last Updated: Jul-13-07 4:45 PM EST –

..., hull speed in miles per hour = the square root of the waterline length x 1.54.

This is different from the formula everybody else on P-net quotes, but that other formula tells you your speed in knots, while this one is miles per hour, which is what you probably need to know. On inland waters, using knots as your unit of measurement makes about as much sense as using furlongs per fortnight.

Now, just remember you can go faster than hull speed if you pour on the power. Sleeker, race-designed boats can exceed hull speed more easily and to a greater degree than regular boats, so I have no clue what the maximum speed might be for "you".

well, aren’t you helpful
that does me no good.

there is a hull speed number, in theory at least, for any boat. i want to know the speed for a J-203.

waterline length?
A quick google suggests that the J-203 is 18.5 feet long, so that formula gives the hull speed as 1.54 * sqrt(18.5) = 6.62 statute miles per hour.

My fairly casual reading of John Winters’s book tells me that the 1.54 number is for “typical” boats. It can vary for boats with narrower or wider bows than typical (I’ve forgotten everything beyond that). Since the J-203 is not typical, I suspect 6.62 is a low estimate.

Are you looking for a better formula, or the results of tank tests, or the results of a computer simulation, or something else? You seem to have something specific in mind.

– Mark

LWL, not LOA
is what you plug into the formula.

Yes, quite helpful, …

– Last Updated: Jul-14-07 12:37 AM EST –

...if you consider the fact that I gave you exactly what you asked for, at least, based on the meaning of the words you used.

Hull speed is the maximum speed a displacement hull can travel without going faster than the waves that it generates. It's a useful number, but as I already said, it's not an actual maximum speed (though for general-purpose paddlecraft it's a very close approximation of the maximum speed unless the paddler is Superman). A racing canoe has the same hull speed as a general-purpose canoe of the same waterline length, but the racing boat will not "hit the wall" as abruptly as speed is increased to hull speed, so going faster than hull speed is within reason. With a general-purpose boat, going faster than hull speed is just not not practical (try this out with your GPS in some boats of different lengths. If you are a good enough paddler to get the boat up to hull speed according to the GPS - try to go faster still, and I bet you'll be surprised how accurate the formula really is).

If there's some OTHER theoretical number you are looking for, it's not called "hull speed". I think the other poster may be right, that what you really want are the results of tank tests. Sorry, I can't help you with that info. The reason there is no other magic number is because the boat will always go faster if you paddle harder, even if only a tiny bit faster.

Depends on who’s paddling it, eh?

Above post is unusually correct and
informative for an internet enthusiast site. Thanks guideboat guy.

OK, i stand corrected
maybe i should have ask: what’s the top speed 203 paddlers have reached in that boat? 6 mph? 7.2? not that i go replicate those numbers. just looking for some type of benchmark. sorry if i sounded snappy. thanks.

Pretty much the same for a J boat
No rocker and plumb ends on those.

Tommy

Pretty Accurate
The formula is accurate and I would add that the power required to propel a displacement hull beyond it’s hull speed is significant in relation to the amount of power required to propel it up to its hull speed. You might have to add something on the order of twice the force to gain a ten to fifteen percent speed improvement.

There are other factors which contribute to a boat’s hull speed such as wetted surface and hull shape which are not considered in LWL. These other characteristics play a part but much smaller than the simple formula based on LWL. So, for most of us the forumula gives us a close enough figure.

Mark

Check
The results page on the New England Canoe and Kayack Racing Assocation Web Page http://www.neckra.org. I know all the C1’s are not J-203’s but they are similar. Speed may vary depending on condition but I would say you will see speeds in the 6 1/2 - 7MPH range.

Again agree
The formula was based on displacement hulls with BWL to LWL ratios quite different than kayaks…but it’s close enough. Lets not forget the difference between potential speed and what a given paddler can actually achieve is a given hull. They may do better in a slightly “shorter” boat given the same cross-section.

i’ve seen higher speeds claimed
in voyagers. surely a 17.5-foot canoe can’t be faster than a marathon. can it? if so, why paddle marathon?

"claimed"
Lots of people “claim” lots of numbers, especially on P-net.

HEX

i’m beginning to think it’s a conspiracy
lol. any semi-accurate numbers will do. i’d hate to resort to comparing race times with distances, math, etc.

Guideboatguy!!
Just curious, I hear alot about hull speed in kayaking,why is this important in a paddle craft?

It seems like 6mph is the norm in any sea kayak.

depending on tide, i cruise at around 4mph.

J-203
The J-203 and J-200 are the same on the bottom the 203 has a narrower gunnel line. On Flatwater a top racer can sprint at or over 8.5 mph. For a 2 hour race on flatwater average speed for a top racer would be 6.5 to 7 mph

It’s only important if you want it to be
People who want a lot of speed are concerned with hull speed. You can look up sites online that explain what it is, but the basic principle is that waves of greater wavelength (the distance from peak to peak or trough to trough) travel faster than waves of shorter wave length. As a boat approaches hull speed, there are just two waves created; one at the bow, and one at the stern. Obviously, the longer the boat, the longer the wavelength of that two-wave set, so the faster those waves will travel. Making your boat go faster than those waves takes tremendous effort in most boats, so hull speed is as fast as the average paddler ever goes.

Is this important? It all depends. You can see that a longer boat will have the potential to go faster than a short boat, but since a longer boat also has more surface area in contact with the water (all else being equal or roughly so), it takes more power to make it move through the water. Thus, unless you need to go fast and are a strong enough paddler to overcome the extra friction, a shorter boat may better, since at “reasonable” speeds it takes less effort to make it go. What this means is that there are a lot of other factors to consider when choosing a boat besides hull speed. I would guess that for MOST people, OTHER aspects about a boat’s length (tracking, seaworthiness, room for storing gear) deserve more consideration than hull speed.

well…
I assume you’d have to figure in the size (weight) of the paddler in different size boats and the type of water you paddling in. Let’s not even get started on technique…but I can vouch for Zav’s paddles on getting you close to where you want to be!