Can someone finally tell me what draft I have?

[Paul Annapolis]

Where do I begin?? The photo was from March of this year and you have had this 2011 boat since when? The name on the bow is "Anywhere" which means you can sail pretty much anywhere there is water....except when there is less than 7' of water. And if there is less than 7', you will have a high degree of confirmation---as if the photo or a tape measure when the photo was taken were not sufficient for confirmation. Tide may be another thing for you to consider and measure when going...anywhere. Now, do you know your air draft or will you wait to measure that against a bridge? By the way, have you ever bought a large piece of furniture?

[aqfishing]

Originally Posted by Paul Annapolis

Where do I begin?? The photo was from March of this year and you have had this 2011 boat since when? The name on the bow is "Anywhere" which means you can sail pretty much anywhere there is water....except when there is less than 7' of water. And if there is less than 7', you will have a high degree of confirmation---as if the photo or a tape measure when the photo was taken were not sufficient for confirmation. Tide may be another thing for you to consider and measure when going...anywhere. Now, do you know your air draft or will you wait to measure that against a bridge? By the way, have you ever bought a large piece of furniture?

[Ringmaster]

How do you buy a boat without knowing what the specs are? If I were shopping I would want the deep draft and wouldn't want a shoal version. So I would look for that.

[Ken Fry]

Originally Posted by Cool Hand Luke

But yeah... it's tough to get a straight, truthful reading.

Oh come on. Next time you hang the boat, put the hook of a tape measure at the waterline, and use the tape as a plumb bob, with the case just touching the ground. (Add the case thickness to the measurement.) Do this on both sides of the boat. Average the measurements.

Then, without putting your hands under the keel, measure its height above
ground, and subtract that from the average.

If this takes more than two minutes after you find a step ladder, you are doing something wrong.

But don't bother with any of that. Your boat draws 7'. (The stuff you will sail over is no where near flat enough to make an inch or two one way or the other significant.) The actual depth changes with with fresh water vs salt water, and more obviously with load. More useful is to run the boat aground gently, and read your depth meter, and calibrate it in some way that makes sense to you (typically, you can make it read 7' or 0'). Lead lines can be handy for such shenanigan's, because charted sandbar depths are rarely correct.

[away again]

Originally Posted by waterman46

Another proof that English system of measurement is more practical. My depth sounder reads in tenths of a foot, not tenths of a meter - so I get three times the precision in my readings compared to you.

We spent a good hour finding our way over a mud bottom into the lagoon in Placencia, Belize. Very shallow for a very long way, but that's where the marinas are. Finally got through the shallow part with about 0.3 feet to spare under the keel and glad we were reading in feet not meters. Also glad for my shoal draft of only 5'6" on our 46' boat.

I know what you mean... 0.3 of a foot is so much more than 0.1 of a metre.
But...
4 inches does not seem as as deep as 10 centimetres

[SeanPatrick]

Here's how you do it:


Next time the boat is on the hard, get your sextant out. (You do have one, right?) Measure off some distance to the boat - say 30 feet - and stand there. Check your index error by lining up the waterline in both the direct and reflected view and note the value. Now sight the bottom of the keel in the direct view and bring the waterline into alignment in the reflected view. Note the reading and add or subtract the index error as required. Take the tangent of the reading and multiply that by the distance off and you have your draft.


So, for example, if you are 30 feet from the boat and you measure 13°08.0' (corrected for index error):


tan(13°08.0') ≈ 2.333



2.333 · 30 = 6.99 ≈ 7 foot draft.


Simple!

[Happ]

Originally Posted by Cool Hand Luke

I have a 2011 Jeanneau Sun Odyssey 409 and to this day I still don't know what draft I have...

According to Sailboat Data:

https://sailboatdata.com/sailboat/su...y-409-jeanneau

My draft is:
Draft (max): 6.89 ft / 2.10 m
OR...
Shoal draft: 1.55m/5.09'

Marina friends tell me that there's no way that my draft is almost 7 feet... but, I also don't think it's 5 feet. See photo attached...

What say ye?

Attachment 226228

Deep keel based on the height of the man washing the bottom. Simple.

[Icarus]

While the boat is out of the water take a tape measure and measure the draught.
Running aground with a fin keel is nof something I would be looking forward to.
Surely it's not rocket science?
Dont worry what the glossy brochures say, the same model might have different keel configuration options .
Like deep draught or shallow draught or anything in between.

[SeanPatrick]

Originally Posted by SeanPatrick

tan(13°08.0') ≈ 2.333



2.333 · 30 = 6.99 ≈ 7 foot draft.

That should be 0.233, not 2.333. That's what I get for using a slide rule.

[JimJohnston]

Originally Posted by SeanPatrick

Here's how you do it:


Next time the boat is on the hard, get your sextant out. (You do have one, right?) Measure off some distance to the boat - say 30 feet - and stand there. Check your index error by lining up the waterline in both the direct and reflected view and note the value. Now sight the bottom of the keel in the direct view and bring the waterline into alignment in the reflected view. Note the reading and add or subtract the index error as required. Take the tangent of the reading and multiply that by the distance off and you have your draft.


So, for example, if you are 30 feet from the boat and you measure 13°08.0' (corrected for index error):


tan(13°08.0') ≈ 2.333



2.333 · 30 = 6.99 ≈ 7 foot draft.


Simple!

Good suggestion. I suspect there are apps that can be loaded onto a phone to accomplish the similar results.

[Ken Fry]

Originally Posted by JimJohnston

Good suggestion. I suspect there are apps that can be loaded onto a phone to accomplish the similar results.

I am concerned that measuring 30 feet from the boat will be difficult for someone who cannot use a tape measure (or cannot just look at the boat pic and say: "oh yes, it's the 7' draft version.").

A laser distance measuring device would be handy for measuring that 30' boat-sextant distance.

Several useful cell phone apps would be good too. First, use cell phone GPS to verify that you are, in fact, in the same marina where your boat is kept. Use a cell phone level application to gauge the slope of the ground. Double check those level readings with the level built into most laser distance measuring devices.

The cell phone calculator can usually be set to the scientific mode, which makes the trig easier to do: we've already seen the horrible mistakes that can occur when using a slide rule!

A cell phone can also be used as the weight on a pendulum, so that a 30' length of string could be obtained by trial and error, by timing the pendulum swing period and doing the math -- again, the math is eased by the cell phone's calculator. Then, that 30' string could be used for sextant positioning.

Another useful cell phone app: Hold the cell phone at the boat's waterline when it is on the hard. Have a friend use his cell phone stop watch to time the fall of your cell phone to ground. Say "GO" when you drop your cell phone. Repeat this 6 times, and average the results. Do the math: use 32' per second per second to get a measurement in feet.

Simple.

[Paul Annapolis]

Ken Fry--too funny!!! And using a rangefinder to check the sextant. HA HA ..as you said--do the math!

[JimJohnston]

Originally Posted by Ken Fry

I am concerned that measuring 30 feet from the boat will be difficult for someone who cannot use a tape measure (or cannot just look at the boat pic and say: "oh yes, it's the 7' draft version.").

A laser distance measuring device would be handy for measuring that 30' boat-sextant distance.

Several useful cell phone apps would be good too. First, use cell phone GPS to verify that you are, in fact, in the same marina where your boat is kept. Use a cell phone level application to gauge the slope of the ground. Double check those level readings with the level built into most laser distance measuring devices.

The cell phone calculator can usually be set to the scientific mode, which makes the trig easier to do: we've already seen the horrible mistakes that can occur when using a slide rule!

A cell phone can also be used as the weight on a pendulum, so that a 30' length of string could be obtained by trial and error, by timing the pendulum swing period and doing the math -- again, the math is eased by the cell phone's calculator. Then, that 30' string could be used for sextant positioning.

Another useful cell phone app: Hold the cell phone at the boat's waterline when it is on the hard. Have a friend use his cell phone stop watch to time the fall of your cell phone to ground. Say "GO" when you drop your cell phone. Repeat this 6 times, and average the results. Do the math: use 32' per second per second to get a measurement in feet.

Simple.

I like the dropped cell phone idea. If I am not mistaken, some phones are equipped with a built in accelerometer. Hence, one need only to start it, drop the phone on location. When you discover the maximum acceleration reached, it should be pretty simple to work backwards (using 32 ft/sec/sec) to find the distance. Voila.

[Cadence]

Did you ever see something so simple so beat to death.