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78Eliminator
06-12-2002, 07:08 AM
I have a (as you might have guessed) 78 Eliminator Daytona. It has a tach, but no speedo. I was thinking about installing one. Do any of you drag boat guys run them or do you just use the GPS method? Just curious.
78Elim

jordanpaulk
06-12-2002, 08:18 AM
go with the GPS for the sake of accuracy.

HavasuDreamin'
06-12-2002, 09:09 AM
Originally posted by jordanpaulk:
go with the GPS for the sake of accuracy.
Absolutely, speedo's are terribly inaccurate plus you have that stupid pilot tube hanging down creating drag resistance.

78Eliminator
06-12-2002, 09:33 AM
HD:
You know you're speed freak when you're worried about the drag resistance of a pitot tube!!!

River Gambler
06-12-2002, 10:32 AM
Why not both!!!!!! put in a gps speedo, they look like a reg. speedo but they are a GPS. No tupe to run, just a small antenna you can place almost anywhere. Originally posted by 78Eliminator:
I have a (as you might have guessed) 78 Eliminator Daytona. It has a tach, but no speedo. I was thinking about installing one. Do any of you drag boat guys run them or do you just use the GPS method? Just curious.
78Elim

HavasuDreamin'
06-12-2002, 10:36 AM
Originally posted by River Gambler:
Why not both!!!!!! put in a gps speedo, they look like a reg. speedo but they are a GPS. No tupe to run, just a small antenna you can place almost anywhere.
Yeah, I have thought about a GPS speedo, but I don't want the thing that looks like a computer mouse anywhere it can be seen. Will a GPS speedo work accurately if you either place the mouse looking thing under the dash or under a seat? The article in ***boat seemed to indicate it needs to be in the open. I'll be damned if that stupid looking thing is going to intrude on the looks of my boat. Any ideas?

Party Cat
06-12-2002, 11:13 AM
Originally posted by HavasuDreamin':
Will a GPS speedo work accurately if you either place the mouse looking thing under the dash or under a seat?
A buddy of mine put his antenna under the deck of his Daytona and only had a problem at the south end of Havasu. From the Channel to past Needles, it worked fine.
YMMV

HavasuDreamin'
06-12-2002, 11:32 AM
Originally posted by Party Cat:
A buddy of mine put his antenna under the deck of his Daytona and only had a problem at the south end of Havasu. From the Channel to past Needles, it worked fine.
YMMV
Cool, I have a dual Gaffrig EGT that hasn't worked from day one. Now there is a big hole in my dash that I think a GPS speedo would fit nicely in. I would either mount the "mouse" under the dash or along my stringer under the seat. This will probably be a winter install though. Thanks.

checkmate76
06-12-2002, 01:28 PM
My speedo is very unaccurate and well I don't want to sound stupid...duh
and i've seen it many times "GPS" but nowhere have I seen what it stands for.
i'm guessing guidance point system?
any help?

Licketty Split
06-12-2002, 01:30 PM
Global Positioning System

mister460
06-12-2002, 01:31 PM
Global Positioning System. Uses satelites.

checkmate76
06-13-2002, 09:52 AM
global positioning huh? that sounds pretty high tech...expensive I'll bet!
Do cloudy days have an affect on this?
how much does this system co$t?
and how accurate is it?

HavasuDreamin'
06-13-2002, 10:11 AM
Originally posted by checkmate76:
global positioning huh? that sounds pretty high tech...expensive I'll bet!
Do cloudy days have an affect on this?
how much does this system co$t?
and how accurate is it?
Extremely accurate, more accurate than radar. Not to expensive. I think you can get the whole set up from Gaffrig for about $300. What did that article in ***boat last month say it cost? I am Mr. Short Term Memory here today..... http://free.***boat.net/ubb/wink.gif

spectras only
06-13-2002, 10:14 AM
A GPS needs to lock on to 3 satellites to work.The problem with them, if you boat around tall mountains.If you loose one satellite ,you loose the triangulation required for positioning.I had one for quite sometime and it's very accurate.My friend is installing a VDO model in a boat that will be used in the ocean where there's less of a chance loosing a satellite,unlike inland boating.

jordanpaulk
06-13-2002, 10:19 AM
I bought a little hand held unit for under $150. I just throw it in a pocket of my soft-sided cooler in the boat. It is usually tracking at least 10 satellites so losing one behind a mountain has never affected it. It is waterproof and floats too. I also take it to Glamis and ride with it in my backpack. One of the coolest things ever. Just my .02
Jordy

HavasuDreamin'
06-13-2002, 10:22 AM
I am going to take a wild guess and say there is no tattle tail on a hand held unit! So how do you know how fast you are actually going. Does someone have to hold this thing and try to read it at 100 mph?

77charger
06-13-2002, 03:52 PM
get the garmin e trex for around a 100 bucks now maybe cheaper it works really good for speed also.
BTW dont get one if you think your boat is faster than what it is though.

jordanpaulk
06-13-2002, 03:58 PM
Originally posted by HavasuDreamin':
I am going to take a wild guess and say there is no tattle tail on a hand held unit! So how do you know how fast you are actually going. Does someone have to hold this thing and try to read it at 100 mph?
There is a tattle tale for everything on my Garmin. It has an odometer, max speed, average speed moving, trip average, current speed, direction, elevation, time of day, moon position and on and on and on. Just reset all the stops in it and make a run. When you stop it will tell you the max speed of the run. Like 77 said, don't get one if you think your boat is faster than it is or if you dont want to know. They call them "Humblers" for a good reason.
Jordy

Torino Jet
06-13-2002, 05:24 PM
I used a GPS a couple of weeks ago, and was reading 59 all day. Lower than I wanted, but what I expected. On the way home, though, hit some rought water. I registered a 75 mph top speed, but I really do not believe I was going anywhere near that. So I wonder how accurate they really are.

77charger
06-13-2002, 05:51 PM
my garmin is really accurate and does'nt fluctuate at all unless you are on the gas.I taped it to my streetbike(01 gsxr 750)and nailed it thru the gears to 4th speedo said 150 gps 135 and i know the speedo on the bike is way off.

LVjetboy
06-13-2002, 11:34 PM
I clocked a Garmin against a vette digital...very close thru 100. My jet speedo reads 1.5 mph below GPS at top speed...not bad either for the much-maligned boat speedo relying on a pitot.
With GPS, I believe bogus readings come from break lock w/satellites, as mentioned by Spectras. So common sense says, go with consistant readings...throw out the occasional "oh my god" reading and you'll be right on.
Also, GPS tends to delay slightly before accurate measurement during acceleration, so allow time to stabilize at top speed. I think the etrex model updates every second, so 5 seconds at speed will get you at least 3-4 updates.
Given that and good signal, you should be within 0.1-0.2 mph of your actual speed.
Great for hiking too.
jer
[This message has been edited by LVjetboy (edited June 14, 2002).]

HavasuDreamin'
06-14-2002, 06:13 AM
Originally posted by jordanpaulk:
There is a tattle tale for everything on my Garmin. It has an odometer, max speed, average speed moving, trip average, current speed, direction, elevation, time of day, moon position and on and on and on. Just reset all the stops in it and make a run. When you stop it will tell you the max speed of the run. Like 77 said, don't get one if you think your boat is faster than it is or if you dont want to know. They call them "Humblers" for a good reason.
Jordy
I've been on radar which is also a humbler, so I feel that I know how fast my boat will go (and yes, I was humbled). I would just like oa GPS to measure speed gains or decreases when trying new props and messing with the jack plate. I think a garmin e-trex or similar is on the shopping list now. Thanks.

Bubbledeck2
06-14-2002, 06:32 AM
You could always get some velcro tape and stick the GPS on your wheel or dash.
I'm not obsessed with my speed, so I only pull it out of my bag when I want to use it.
I'd say mine is within a tenth of a mile an hour as far as accuracy.
Garmin E Trex $120 at Best Buy

SUPERCREWJOHN
06-14-2002, 08:04 AM
Originally posted by checkmate76:
global positioning huh? that sounds pretty high tech...expensive I'll bet!
Do cloudy days have an affect on this?
how much does this system co$t?
and how accurate is it?
Pretty high tech for a monkey.. Not much more sophisticated than a cell phone, 100 times more reliable than a speedometer, and they look cool..

TX19
06-15-2002, 03:42 PM
I was curious to see if my 10 year old Nordskog speedometer is accurate so I borrowed a GPS and an operator and checked it out. The Nordskog was right on the button at anything over 50 mph. I was very suprised. The GPS we used was a Magellan. I think it was a model 620 but I am not sure about the model.
Others are right about replacing the pitot tube. I go through about 4 or 5 every season. Most times I don't realize I hit anything until the speedometer really slows down or it doesn't work at all.
Has anyone had any success with any of the high dollar spring loaded pitot holders that are spring loaded? That investment may be a good one if it saves a few pitot tubes.

LVjetboy
06-16-2002, 12:48 AM
I'm sure I've hit things with my 11 year pitot, little dog ears long gone. If the inlet hole's not distorted or plugged, I don't think the dog ears make much difference. But those spring-loaded jobs sure look cool. Maybe some day...

bp
06-16-2002, 03:13 PM
i have a garmin xl12 that i strap to my knee when i'm just foolin' around, trying to figure out what speed equates to a steady rpm.
i also have a pitot going to a speed transducer and then to the edelbrock quikdata. we've found this setup to be extremely accurate. there's no speedometer to look at; besides, who has time to look at gauges when you're going 0-90 in 7 seconds? http://free.***boat.net/ubb/smile.gif

GasTurbine
06-19-2002, 08:15 AM
Originally posted by 78Eliminator:
HD:
You know you're speed freak when you're worried about the drag resistance of a pitot tube!!!
Yea? Well check out this thread...
http://free.***boat.net/ubb/Forum11/HTML/000238.html

Old Guy
07-04-2002, 05:53 AM
About 15 or so years ago I had a boat with a very inaccurate speedo. I wondered if they were all useless like everybody said or not. I called Teleflex in Sarasota, Fla. and talked to their cheif engineering person (a very nice, friendly fella). He told me that they used to sell speedometers to boat manufacturers and often make them (at the customers request) read faster than was true speed because it was easy to convince people that they were really going that fast. He said that at one point it got so bad that his company refused to sell a speedometer that was more than 3% off. He also gave me the following interesting (but probably useless) information so that I could check the calibration of any speedometer. You put a tee in the hose from the pitot tube and attach a VERY ACCURATE (don't know where to get one) presure gage. The gage and speedo reading should be as follows.
5.3psi = 20mph
7.46psi = 25mph
10.9psi = 30mph
14.8psi = 35mph
19.36psi = 40mph
24.5psi = 45mph
30.25psi = 50mph
43.56psi = 60mph
WOW....sorry about the length. Now I can throw my note away.

HammerDown
07-04-2002, 10:00 AM
Thats interesting stuff...I was in a friends boat, and comparing his cheep speedo to his gps...and to my suprise...the speedo was only off a mile or two thru out the entire rmp range.

coolchange
07-04-2002, 10:13 AM
Hey Oldguy, cool info I'm writin' it down now. Thanx!