Has anyone used a GPS to see fast there 170 will go? Does 1.34 X root waterline lenght theory apply or is it considered a planing hull? This weekend, first time out in 15 plus knots, I suspected that I was planing? It seemed as though I was going really fast anyways. James
170 Speed
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Well, this is just my first year so I am probably not getting maximum speed yet, but I have recorded 6.5 mph on my GPS with my 170, winds were aabout 10-12 knots (slight chop, rare whitecap). The more I sail my 170, the more fun I am having. Went out last week with a couple of guys who wanted to see what the 170 would do. Winds were in the 15+ knot range, with the weight of the 3 of us up on the rail, we were able fly both main and jib on a close reach, but still able to stay almost flat on the water, unfortunately I did not have my GPS but it felt like we were flying!
I have not carried my GPS on board yet but now that I have a small dry bag I can put it in I will try it. I can tether it to the mainsail block on the floor. Hopefully, I wont step on it. I will give it a shot in two weeks when I am back in town.
gps reading in 10-15 knot winds
Had my GPS stating 6.4 mph in 10 knot winds last week. Had two kids aboard and could have been more aggressive, but believe this is near a max speed unless you can get the hull to plane like some of the posts to this message. Hunter refers to teh 170 as a semi-displacement hull.... I do not believe i have come near to planing yet. phil
Had my GPS stating 6.4 mph in 10 knot winds last week. Had two kids aboard and could have been more aggressive, but believe this is near a max speed unless you can get the hull to plane like some of the posts to this message. Hunter refers to teh 170 as a semi-displacement hull.... I do not believe i have come near to planing yet. phil
MPH vs KPH
Please help me refresh my memory. What is the realtionship between Miles per hour and Knots per hour?
Please help me refresh my memory. What is the realtionship between Miles per hour and Knots per hour?
MPH vs KPH
Grady: There is no such thing as KPH (unless you are talking acceleration, and I'm sure you aren't). The word "knots" stands for nautical miles per hour. The relationship between the two is that a land mile is 5,280 feet. A nautical mile is 6,000 feet or 2,000 yards, so one knot (one nautical mile per hour) is a little faster than a land mile per hour since you are covering slightly more distance in the same period of time, one hour.
Grady: There is no such thing as KPH (unless you are talking acceleration, and I'm sure you aren't). The word "knots" stands for nautical miles per hour. The relationship between the two is that a land mile is 5,280 feet. A nautical mile is 6,000 feet or 2,000 yards, so one knot (one nautical mile per hour) is a little faster than a land mile per hour since you are covering slightly more distance in the same period of time, one hour.
Sails right along.
I've seen 6 knots for a while on a sort of close reach w/ 3 adults aboard. 5 knots all day long. Good wind, no whitecaps, but on a river. Haven't had the Spinnakker up yet
I've seen 6 knots for a while on a sort of close reach w/ 3 adults aboard. 5 knots all day long. Good wind, no whitecaps, but on a river. Haven't had the Spinnakker up yet
new experiences with 170
I've just tested my new 170 for the last 4 weeks and prepared the GPS for the purpose of mesuring max speed. Of course, I did not have it with me when we were doing our best However, my feeling is we got over 7+ knots in 10-15 knot winds. Precise measurement will have to wait for the next season. Haven't tried the spi kit either (which I received too late).
I've just tested my new 170 for the last 4 weeks and prepared the GPS for the purpose of mesuring max speed. Of course, I did not have it with me when we were doing our best
However, my feeling is we got over 7+ knots in 10-15 knot winds. Precise measurement will have to wait for the next season. Haven't tried the spi kit either (which I received too late).Planing over 5.2 knots
If you get a boat well over it's hull speed, you are riding up on the bow wave - that's the definition of planing. With a hull speed of 5.2 knots, the 170 is certainly planing at any speed over 6 knots, regardless of how it feels. Do remember that the GPS also measures the contribution of any currents to your boat's speed over ground. So doing 6.5 knots with a 2 knot current is 4.5 knots through the water, and well below hull speed. David Lady Lillie
If you get a boat well over it's hull speed, you are riding up on the bow wave - that's the definition of planing. With a hull speed of 5.2 knots, the 170 is certainly planing at any speed over 6 knots, regardless of how it feels. Do remember that the GPS also measures the contribution of any currents to your boat's speed over ground. So doing 6.5 knots with a 2 knot current is 4.5 knots through the water, and well below hull speed. David Lady Lillie
You can't go over your hull speed....
and if you are, then you are either planing, surfing, or freefalling. Law of physics. And, like David said, you can't trust your GPS on your speed. GPS tells you your speed over ground. What you really need is to use the boat's speedo, it shows your boat's speed measured against the water.
and if you are, then you are either planing, surfing, or freefalling. Law of physics. And, like David said, you can't trust your GPS on your speed. GPS tells you your speed over ground. What you really need is to use the boat's speedo, it shows your boat's speed measured against the water.
Perfect speed?
Whether you use a GPS or a boat-mounted speedo to measure your velocity sort of depends on what's important to you at the moment. As an airplane pilot as well as a (low-time) sailor, I needed my aircraft mounted airspeed indicator for purposes of knowing when I was within the design envelope of the plane. Airspeed is important to keep the plane in the air ,but really only tells you how fast the air is moving over the surface of the plane. For the boat, which will remain afloat in spite of NO water flow over it's hull, a device that measures your actual progress from point A to point B over the earth's surface may be even more useful. Youy can anchor your boat in a river with a 20 knot current flow and your boat's speedo will show your speed as 20 knots, but you're still not getting anywhere. Or, you could put a telemetry setup on a boat and send it over Niagara (sp?) Falls. All the way to the bottom, the boat's speedo would read zero knots relative to the water it was in, but the result would suggest that something else was going on. In the end, I suppose that boat speedos are useful for relative measurements, as well as entertaining the skipper. My former H216 would approach planing with my wife and I aboard ,then the weather helm would overwhelm the rudder and it would quickly round up. I've sailed an H146 which moved pretty well, and currently have a JY15 which shows the potential for planing. Has anyone actually had an H170 on a plane? Bob Cowgill Cocoa, Florida
Whether you use a GPS or a boat-mounted speedo to measure your velocity sort of depends on what's important to you at the moment. As an airplane pilot as well as a (low-time) sailor, I needed my aircraft mounted airspeed indicator for purposes of knowing when I was within the design envelope of the plane. Airspeed is important to keep the plane in the air ,but really only tells you how fast the air is moving over the surface of the plane. For the boat, which will remain afloat in spite of NO water flow over it's hull, a device that measures your actual progress from point A to point B over the earth's surface may be even more useful. Youy can anchor your boat in a river with a 20 knot current flow and your boat's speedo will show your speed as 20 knots, but you're still not getting anywhere. Or, you could put a telemetry setup on a boat and send it over Niagara (sp?) Falls. All the way to the bottom, the boat's speedo would read zero knots relative to the water it was in, but the result would suggest that something else was going on. In the end, I suppose that boat speedos are useful for relative measurements, as well as entertaining the skipper. My former H216 would approach planing with my wife and I aboard ,then the weather helm would overwhelm the rudder and it would quickly round up. I've sailed an H146 which moved pretty well, and currently have a JY15 which shows the potential for planing. Has anyone actually had an H170 on a plane? Bob Cowgill Cocoa, Florida
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