Draft question

Yellowjeepman

Yellowjeepman

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Apr 26, 2014
30
Oday 34 Cape coral yacht basin
Just a newbee question. I have an O'Day 34 listed as having a 4'3" draft. I assume this is dry weight, not having my 50 gallons of fresh water tanks filled and fuel tank filled or any gear aboard. Am I correct ?Does it take a lot of weight to change this ? There are just the 2 of us aboard and there is so much skinny water with many turns and power boat owners which always feel they have the right of way. How much weight approximately does it change to affect my draft. I always keep at least 5 + ft. of water below by transducer which is at the lowest point of my hull possible. I have my boat at the Cape Coral Yacht Club and although its a great marina, its about 10 miles of ICW travel to areas of deeper water. Thank you for your help
Frank
 
Ariel

Ariel

.
Feb 1, 2006
279
Pearson 36-2 Houston, TX / Rock Hall, MD
Here is the formula. You can calculate your own:


POUNDS PER SQUARE INCH IMMERISON

Multiply the waterline length by waterline beam, and multiply that figure by 0.76. This will be the boat’s waterplane area in square feet.

Now, multiply this by 5.33 for salt water (or 5.32 for fresh water). This number is how many pounds it takes to sink the boat about 1”.

For my Pearson 36, this is about 1200 lbs.
Skene’s Elements of Yacht Design nomograph showes 1130 lbs. for another reference of a boat my size.

Dave
s/v ARIEL
 
31seahorse

31seahorse

.
Aug 2, 2005
1,155
Pearson 33-2 & Typhoon 18 Seneca Lake
Hello Frank and welcome to a great area for your wonderful boat.

I am NOT an engineer, but I do not think crew and water tank filling will add much to your draft. Also. consider that your transducer is reading from its location in the hull on down to the sand. If you are staying in 5 foot deep water as a reading you probably are in 6+ feet of water from surface to sand. We owned an O'day 34 and loved it for cruising and daysailing!

Are you familiar with the area? There are many wonderful places to sail, anchor, visit, etc. Good charts and a GPS will make your sailing less worrisome concerning depth. Watch for extremes of tide and wind conditions from the North/Northwest that may bring about shallow conditions. Being careful is the answer including paying attention to your direction in the river, in a channel, and in the ICW. Best Wishes!
 
centerline

centerline

.
Mar 20, 2012
3,983
Cal 34-III, MacGregor 25 Salem, Oregon
31seahorse said:
consider that your transducer is reading from its location in the hull on down to the sand. If you are staying in 5 foot deep water as a reading you probably are in 6+ feet of water from surface to sand.
Click to expand
one word of caution.... you really need to find out if someone has set the offset of the transducer to the depth of the vessel draft, or if it is measuring from where the transducer is installed.... if the transducer is installed in the bottom of the keel, then it will all be the same and it doesnt matter.
 
Yellowjeepman

Yellowjeepman

.
Apr 26, 2014
30
Oday 34 Cape coral yacht basin
Thank you everyone for the great and fast replies. I really appreciate you replies
Frank
 
Joe

Joe

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Jun 1, 2004
8,318
Catalina 27 Mission Bay, San Diego
My depth meter is calibrated to offset the difference between waterline and transducer location. Get out your depth sounder's owner's manual if you're not sure about your set up... Even if the offset hasn't been calibrated you are on the safe side of the error.

I like the formula provided by Ariel... but if you're quite unsure about the existing waterline.... pull out the Sharpy and mark a small rule on the boat when it's unloaded... with a few incremental marks upward to help you visualize what's happening when you add your payload of gear and crew.
 
Ron20324

Ron20324

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Jan 22, 2008
8,050
Beneteau 323 Annapolis MD
I'm away from home to pull the information, but if IIRC, new boat reviews often say some figures are calculated with a (half tank?) of gas and of water, with (2?) people aboard.
 
seadaddler

seadaddler

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Dec 19, 2006
5,832
Hunter 36 Punta Gorda
Draft

I am in charlotte harbor and my draft 4'10'' but what I have done is load the boat with anything and everything that you take with you when going sailing
and than make sure you have a flat bottom under you boat and drop some kind
of measuring like a line with marks on it for 1 to 5' and drop it over the side
as close to where the keel is and see what the dept is and check it against your guage.
My dept gauge tells me what the dept of water I am in and this way if I am in 10 ft or 6 ft it's a no brainer I always know I need 5 ft of water and this way I always know how much water I need my 2 cents.
I also drop this line I carry with a lead weight and marking on it with me and when ever I anchor I always check to make sure everything is OK.
As you may know 5' is alot of draft for this area and have most times not stuck
but have run aground for sure.
Nick
 
Bob J.

Bob J.

.
Apr 14, 2009
775
Sabre 28 NH
Yellowjeepman said:
There are just the 2 of us aboard and there is so much skinny water with many turns and power boat owners which always feel they have the right of way. Frank
Click to expand
Just put a sail up when you're motoring out of the place & technically it turns the tables in your favor :)
 
Bob J.

Bob J.

.
Apr 14, 2009
775
Sabre 28 NH
Kermit said:
Not really.
Click to expand
I understand what you're saying Kermit. I did use the word "technically" & fact is it's wrong. If the sails are up & the motor is operating, you're motoring.

I guess what I meant was whenever I saw a boat with the sails up, I yielded to them. I had no idea if they were motoring or not & frankly didn't care. As a former powerboater it just seemed like the right thing to do, even if they were rag merchants.
 
Kermit

Kermit

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Jul 31, 2010
5,722
AquaCat 12.5 17342 Wateree Lake, SC
Now that I agree with. But wait. A power boater that yields to sailboats? Will wonders never cease! :)
 
rgranger

rgranger

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Jan 19, 2010
12,935
Hobie 16 & Rhodes 22 Skeeter Charleston
Misfits said:
Just put a sail up when you're motoring out of the place & technically it turns the tables in your favor :)
Click to expand
Technically.... If you turn your motor on with your sail up, you need to turn on your steaming light so other power boats know they can legally run you over... :D
 
Joe

Joe

.
Jun 1, 2004
8,318
Catalina 27 Mission Bay, San Diego
Misfits said:
I understand what you're saying Kermit. I did use the word "technically" & fact is it's wrong. If the sails are up & the motor is operating, you're motoring.

I guess what I meant was whenever I saw a boat with the sails up, I yielded to them. I had no idea if they were motoring or not & frankly didn't care. As a former powerboater it just seemed like the right thing to do, even if they were rag merchants.
Click to expand
Don't forget, that besides the steaming light on the mast, displaying a dayshape is recommended..... though... in my 16 years sailing in and around San Diego... I have never seen a sailboat under power display the inverted triangle dayshape.
http://www.boatsafe.com/nauticalknowhow/ansshape.htm
 
justsomeguy

justsomeguy

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Feb 20, 2011
8,062
Island Packet 35 Tucson, AZ/San Carlos, MX
rgranger said:

Not under command...

I should just wear that on my t-shirt:dance:

... or maybe when out carousing I could wear a t-shirt with...


Restricted
Maneuverability
:D
Click to expand
Great idea for a tee shirt...
 
woodster

woodster

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Sep 15, 2009
6,244
S2 9.2a Fairhope Al
rgranger said:

Not under command...

I should just wear that on my t-shirt:dance:

... or maybe when out carousing I could wear a t-shirt with...


Restricted
Maneuverability
:D
Click to expand
man you have a very quick and diversed mind:D :theman:
 
justsomeguy

justsomeguy

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Feb 20, 2011
8,062
Island Packet 35 Tucson, AZ/San Carlos, MX
Oh, it's diversed. I love things that make people want to know what they're about, like your tee shirt idea.

Please rise. I'm not worthy. :D
 
Kings Gambit

Kings Gambit

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Jul 27, 2011
5,180
Bavaria 38E Alamitos Bay
Joe said:
Don't forget, that besides the steaming light on the mast, displaying a dayshape is recommended..... though... in my 16 years sailing in and around San Diego... I have never seen a sailboat under power display the inverted triangle dayshape.
http://www.boatsafe.com/nauticalknowhow/ansshape.htm
Click to expand
How many recreational powerboaters would know what the dayshape meant even if it were displayed and if they even noticed it? I doubt many.
 
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