Hello, I've recently bought a 1993 Hunter 23.5 and am very happy with it. I've also recently discovered this forum and have found your many postings very informative and useful. Now I've got a question. Last weekend was my first outing on my boat. Air temperatures on Biscayne bay were in the high 80s and a steady breeze was blowing out of the east at 10-15 knots. As I played around with different headings on both tacks, I found that the best speed I could do (according to my autohelm) was 3.5 knots. While I know that many variables go into the final speed that the boat makes good, I'm wondering about the experiences of other sailors under these wind conditions. Is that about the speed I should expect on a favorable tack under these conditions? I'm just looking at the distances from me to certain Keys and thinking about the travel time I might need. Thanks for your input. Michael
- Status
- Not open for further replies.
R
Russell
Speed? Hope your not going far
I think you are seeing a real low speed. I have a 240 and would expect at least 4.5 knots or more out of those conditions. I have an Auto Helm Bi data, and each season I have to clean the hull around it and the paddle wheel itself, or I slow down to. I think that may be the case for you as well Russell Rhudson72@aol.com s/v Summer Luvin'
I think you are seeing a real low speed. I have a 240 and would expect at least 4.5 knots or more out of those conditions. I have an Auto Helm Bi data, and each season I have to clean the hull around it and the paddle wheel itself, or I slow down to. I think that may be the case for you as well Russell Rhudson72@aol.com s/v Summer Luvin'
R
Rick Webb
Somthings Off
On my 23.5 according to my GPS I reularly get 4-5 kts and have had it up above 7 kts. Seems like your getting a false reading, do you have a GPS?
On my 23.5 according to my GPS I reularly get 4-5 kts and have had it up above 7 kts. Seems like your getting a false reading, do you have a GPS?
M
Mike DiMario
Formula
Dear Michael, Congradulations on the purchase of your new boat. There is a formula for the theoretical maximum hull speed for a displacement type hull. There is no reason why you should not get close that calculation. The formula is the square root of the length at the waterline (low) for your boat multiplied by 1.34. ( some say 1.41). You can get the length of your boat at the waterline right here on the HOW in boat specs area. Your speed instrument is more likely than not adjustable. Usually you run a measured mile to calibrate it. Good luck and happy sailing, Mike D. Media, PA s/v Serenity H376
Dear Michael, Congradulations on the purchase of your new boat. There is a formula for the theoretical maximum hull speed for a displacement type hull. There is no reason why you should not get close that calculation. The formula is the square root of the length at the waterline (low) for your boat multiplied by 1.34. ( some say 1.41). You can get the length of your boat at the waterline right here on the HOW in boat specs area. Your speed instrument is more likely than not adjustable. Usually you run a measured mile to calibrate it. Good luck and happy sailing, Mike D. Media, PA s/v Serenity H376
M
Michael McClain
Good ideas
Thanks for the good points. I'm relieved to learn that I shouldn't be creeping through the Keys at less than 4 knots! I checked the paddlewheel (I also have a Bidata-ST30) and found it mostly clean and free spinning. There was a little tick with each rotation, but I'm guessing that is counting to calculate speed. Maybe it's a calibration problem? I'll try to check it tomorrow when I'm out again. I do have a GPS but did not take it out that first time. I'll take it out and make some comparisons. According to the formula Mike provided, I should be able to approach 6 knots. Ahh! Suddenly those Keys feel a lot closer. Michael
Thanks for the good points. I'm relieved to learn that I shouldn't be creeping through the Keys at less than 4 knots! I checked the paddlewheel (I also have a Bidata-ST30) and found it mostly clean and free spinning. There was a little tick with each rotation, but I'm guessing that is counting to calculate speed. Maybe it's a calibration problem? I'll try to check it tomorrow when I'm out again. I do have a GPS but did not take it out that first time. I'll take it out and make some comparisons. According to the formula Mike provided, I should be able to approach 6 knots. Ahh! Suddenly those Keys feel a lot closer. Michael
B
Been there
Several points
Hull speed, whose formula Mike gave, is not a theoretical maximum. It is the speed in water of a wave the length of the waterline. The energy to maintain speed for a displacement hull tends to increase dramatically about that speed. But the curve remains smooth. Some boats never reach hull speed. Others regularly exceed it. Multihulls laugh at it. I don't know the Hunter 23.5, but an old Hunter 23 easily hits 6 knots under working canvass and any breeze over 10 knots. Finally, most speedos are off. Some by a little, others by a lot. They typically read more on one tack than the other.
Hull speed, whose formula Mike gave, is not a theoretical maximum. It is the speed in water of a wave the length of the waterline. The energy to maintain speed for a displacement hull tends to increase dramatically about that speed. But the curve remains smooth. Some boats never reach hull speed. Others regularly exceed it. Multihulls laugh at it. I don't know the Hunter 23.5, but an old Hunter 23 easily hits 6 knots under working canvass and any breeze over 10 knots. Finally, most speedos are off. Some by a little, others by a lot. They typically read more on one tack than the other.
B
Bob and Pauline
Speed-paddle wheel
Look at the paddle wheel again to determine if the wheel has been installed correctly. Some where installed with the curved surface catching the water and it should be turned around so the flat edge hits the water each time it rotates.
Look at the paddle wheel again to determine if the wheel has been installed correctly. Some where installed with the curved surface catching the water and it should be turned around so the flat edge hits the water each time it rotates.
Here's another trick for checking speed
The March 2000 issue of Cruising World has an article called "Never Lost" which includes a simple way to check your boatspeed. Have your crew toss something small, floating and biodegradable (e.g. a potato chip) off the bow and time how long it takes for the stern to go by it. If you know your boat's length you can easily calculate your speed in feet per second, which you then multiply by 0.5925 to get the speed in knots. OK, I admit it is pretty low tech but it is the principle of the original chip log. Besides, a can of Pringles and a simple solar calculator are a lot less expensive than a GPS, and the batteries will never run down..... Peter s/v Raven
The March 2000 issue of Cruising World has an article called "Never Lost" which includes a simple way to check your boatspeed. Have your crew toss something small, floating and biodegradable (e.g. a potato chip) off the bow and time how long it takes for the stern to go by it. If you know your boat's length you can easily calculate your speed in feet per second, which you then multiply by 0.5925 to get the speed in knots. OK, I admit it is pretty low tech but it is the principle of the original chip log. Besides, a can of Pringles and a simple solar calculator are a lot less expensive than a GPS, and the batteries will never run down..... Peter s/v Raven
M
Michael Cohn
Good trick
I've done the toss something off the bow and time it trick a few times myself. It really does work pretty well, but, of course, you definitely want to use something biodegradable. Barbeque flavor Pringles seem to give the most accurate results, although I once found out that dolphins like them a lot - not one of my chips ever made it past the stern on that occasion. One of the dolphins finally checked his internal knotmeter, and said to me, "All I can tell you is that you're going a LOT slower than I am" and swam off... MC
I've done the toss something off the bow and time it trick a few times myself. It really does work pretty well, but, of course, you definitely want to use something biodegradable. Barbeque flavor Pringles seem to give the most accurate results, although I once found out that dolphins like them a lot - not one of my chips ever made it past the stern on that occasion. One of the dolphins finally checked his internal knotmeter, and said to me, "All I can tell you is that you're going a LOT slower than I am" and swam off... MC
U
uncle.al@wcnet.net
recent experience
i have a garmin 126 gps installed yesterday i sailed on galveston bay and the winds were maybe 15 and a very low sea state -- 1-2 ft the gps showed i got up to 6.4 knots on a broad reach
i have a garmin 126 gps installed yesterday i sailed on galveston bay and the winds were maybe 15 and a very low sea state -- 1-2 ft the gps showed i got up to 6.4 knots on a broad reach
- Status
- Not open for further replies.