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Foredeck Shuffle

Member Since 09 Sep 2004
Offline Last Active Aug 24 2016 04:28 PM
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Posts I've Made

In Topic: What is the secret of upwind planing

24 August 2016 - 04:29 PM

This.

 

So many boat owners think they are planing when their boat is clearly surfing, going partially through waves not really over.  Having driven a 505 doing 9 upwind and then turning down, the amount of boat in the water and the way the boat tracks changes dramatically.

 

I don't think the modern skiff style hulls truly plane upwind.  They achieve planing speeds, but tend to keep the bow knuckle just touching the water.  I think the hull behaves more like a catamaran hull in that they don't really develop much of a wake.


In Topic: Dinghy VPP's?

18 August 2016 - 03:47 PM

I almost put on a different rudder to the boat but at that point it's going too far.  This is a cheap project for fun and self entertainment.  I bet a rudder from an Aero would be ideal?

 

i remember hearing/reading about the theoretical top speed of a laser being around 20kts, due to the limitations of the rudder maintaining flow... the chart seems to fit with that idea/memory.


In Topic: Dinghy VPP's?

18 August 2016 - 03:42 PM

And we have a route for a Standard Rig Laser with today's predicted wind with a resolution of 1hr and .25nm.  This route is unlikely to be conditions for the race, it rarely blows out of the NW this time of year.  Not sure why Expedition thinks I can go 8 degree off the wind, will need to look into that.  It will be a beat down the Bay (pun intended) but very manageable in similar winds.  It's a GO prediction putting me at the bar before it is even opens.  Hadn't thought of that, will make sure that I have a cooler with iced beer staged in the tow vehicle.  Planning is everything!

Eastern Daylight Time	Twd°M	Tws	Twa	Targ	Bsp	Brg°M	Tack	Dist nm	Mode	Latitude	Longitude
08/18/2016 10:51	335°	9.3	-147°	152°	6.9	122°	Port	0.62	Sail	38 19.025n	076 24.063w
08/18/2016 10:57	335°	9.3	-147°	152°	6.9	122°	Port	0.62	Sail	38 18.804n	076 23.325w
08/18/2016 11:02	335°	9.3	-147°	152°	6.9	122°	Port	0.62	Sail	38 18.583n	076 22.586w
08/18/2016 11:07	335°	9.4	-147°	152°	6.9	122°	Port	0.62	Sail	38 18.361n	076 21.848w
08/18/2016 11:13	334°	9.4	(174°)	152°	6.7	160°	Strbd	3.46	Sail	38 18.140n	076 21.110w
08/18/2016 11:48	333°	9.4	151°	152°	6.7	182°	Strbd	3.89	Sail	38 15.166n	076 18.847w
08/18/2016 12:23	332°	9.1	149°	152°	6.7	183°	Strbd	3.67	Sail	38 11.328n	076 18.049w
08/18/2016 12:56	333°	8.7	127°	151°	7.4	205°	Strbd	3.19	Sail	38 07.688n	076 17.415w
08/18/2016 13:23	335°	8.2	130°	150°	7.1	205°	Strbd	3.19	Sail	38 04.593n	076 18.413w
08/18/2016 13:50	337°	7.5	(8°)	041°	5.8	329°	Strbd	2.83	Sail	38 01.498n	076 19.409w
08/18/2016 14:29	344°	6.8	(18°)	042°	5.5	326°	Strbd	2.71	Sail	38 03.599n	076 21.814w
08/18/2016 15:07	352°	6.1	22°			326°	Strbd		Sail	38 05.517n	076 24.250w
											
Route distance	25.25nm										
Optimal distance	27.34nm										
Optimal route time	4h 15m 28s										
Created	08/18/2016 11:24										
Sail chart											
Polar	Laser										
Polar %	100										
Model	GFS										
Current											
Wind %	100										
Algorithm	Grid based										


In Topic: Dinghy VPP's?

18 August 2016 - 03:16 PM

So I found a decent set of polars, then used the Bethwaite polars and fudged the in between #'s by using the incremental seen in the polar graph of real recorded numbers and when the boat seems to plane and came up with this.  Not perfect but suitable for what I want to do.

!Expedition polar																								
2.0	35	1.2	40	1.4	50	1.5	60	1.6	75	1.7	90	1.8	105	1.7	120	1.6	135	1.5	150	1.4	165	1.3	180	1.1
4.0	35	2.5	40	2.8	50	3.0	60	3.1	75	3.2	90	3.2	105	3.1	120	3.0	135	2.9	150	2.6	165	2.4	180	2.1
6.0	35	3.0	40	4.0	50	4.5	60	4.7	75	4.9	90	5.4	105	5.3	120	5.2	135	5.0	150	4.6	165	4.3	180	4.1
8.5	35	3.1	40	4.3	50	5.0	60	5.6	75	6.0	90	6.4	105	6.5	120	6.3	135	6.2	150	6.1	165	6.0	180	5.9
10.0	35	3.1	40	4.5	50	5.1	60	6.0	75	6.5	90	6.9	105	7.1	120	7.2	135	7.1	150	6.8	165	6.4	180	6.3
12.0	35	3.2	40	4.8	50	5.2	60	6.3	75	7.0	90	7.4	105	7.7	120	8.1	135	8.0	150	7.4	165	6.8	180	6.7
13.5	35	3.2	40	4.9	50	5.4	60	6.5	75	7.3	90	7.5	105	7.9	120	8.5	135	8.7	150	7.9	165	7.1	180	7.0
16.0	35	3.3	40	5.2	50	5.7	60	6.7	75	7.7	90	8.8	105	9.9	120	10.3	135	10.3	150	9.5	165	8.7	180	8.6
19.0	35	3.4	40	5.3	50	6.0	60	7.0	75	8.1	90	10.0	105	11.9	120	12.0	135	11.8	150	11.1	165	10.7	180	10.5
22.0	35	3.5	40	5.4	50	6.2	60	7.5	75	9.2	90	12.4	105	13.8	120	13.8	135	13.7	150	12.6	165	12.1	180	11.8
25.0	35	3.6	40	5.5	50	6.4	60	7.9	75	10.2	90	14.8	105	15.6	120	15.5	135	15.4	150	14.0	165	13.4	180	13.0
30.0	35	3.7	40	5.6	50	6.7	60	8.2	75	11.8	90	18.0	105	19.7	120	19.4	135	19.0	150	18.7	165	18.0	180	17.9

In Topic: Dinghy VPP's?

18 August 2016 - 03:14 PM

I used to race a 505 out of WRSC, always jealous of the A-Cat's so I asked to take one out, guess that was somewhere around 2009.  I've always kicked myself for getting a 3rd 505 rather than an A-Cat, or even an F-18.  Was it 2010 that a large F-18 event was held?  I went out to watch the racing.  In 2013 I was going to get an F-18 to do the Tybe 500 but found out they have stopped having the race.  If that ever comes back I'm definitely going to get an F-18 and practice up.

 

You don't have to sell this to me, it's obvious.  If I didn't already have a job on a boat in SMSA for a distance race for the 10th for Oxford I'd beg and bribe for a ride if anyone on a F-18 or NACRA is short crew.  Always forget about that race and that the cat's do it, I need to plan better that would be an awesome ride.

 

I'm not sure how wise taking an F-18 into an adventure race is as the water depth for the courses can go to as low as 2'.  I would have to have a way to keep the boards up reliably, or just get a spare set of straight, short boards so that I do not weep during the race when ever they take a hit.  There is also the issue that some of the bridges you have to go under can be 4'-10' in height, wonder how quick I can unstep and restep an F-18?  The races are always multiple days long so unstepping is a common occurrence.

 

So why do the Laser in distances?  Because used hulls that are not soft are easy and cheap to buy, reasonably quick for its size, and because its hard to do.  But a cat is definitely in future plans.

 

Wess, that's on the F18 with the monster gumbo boards (we draw 5.5') and latest sailplan in flat water. Typically out in the short chop in the bay we are tacking through more like 80 degrees, it is a very rare performance monohull that has better tacking angles in said conditions. An old IOR boat may point higher but we will roll them to leeward and move on with our day...The N20 is more in the 90 range as they have a lower aspect ratio jib and mainsail, lower aspect less efficient boards and can't quite point as high when we are in double trap mode upwind. My numbers are from GPS data collected on the boat and compared with NOAA buoy data, current was not subtracted so it is possible we had a current boost, but my targets on the N20 were in the 12.5kt range upwind as well in the ocean with less tidal effects (but possible gulfstream push).

 

You are more than welcome to come give my boat a go any day the breeze is up and validate said statements :). Certainly in more typical Chesapeake light breeze conditions our tacking angles are down in the 90's and 100's.

 

I too would love VPP's for these boats but no one has them to my knowledge. I'm sure some exist for the Tornado and N17 in the collective hands of the worlds best Olympians, but shaking that data loose (at least on the 17) is unlikely.