Speedo's..GPS??

[jet]

Need your opinion?? Last 4th July I took my boat to a new lake that I was not familiar with. So I thought?? Why not take my GPS (I used it in Hawahii on my friends boat) so why not here? I used it while I was there and it was awesome! I ended up trailering the boat after dark every night so I had to go across the lake and the gps showed me where NOT to go and then showed me the line i took the night before so i wouldn't hit any shallow water, logs or dams! lol. So i was thinking..the speedos we have work sometimes and they are old..why not pull them, make a new dash template and snap in a gps?? If i ever get PP it will use a paddle wheel and not the dash speedos..so why not? Cheeezee?? Or not? I think its a great idea, what do you think? Jet

[csuggs]

If you want navigation capabilities then GPS is the way to go. If you just want an accurate indication of speed, then I think the speedos are fine. Mine used to be like yours and work only some of the time. But since I replaced the pitot tubes with the tournament style flow through ones, and replaced all the old 1/4" tubing from the pitot tubes to the speedos - I have no trouble at all. And I believe they are very accurate. After each time I pull the boat out of the water, I run a metal wire through the pitot tube to be sure it's cleaned out good. I'm happy with that, but then where I go boating, I don't need any navigation devices. However, Jim @ Viper is installing a dash mounted depth finder in place of the factory analog clock that doesn't work anymore. Of course there are the paddle-wheel type speedos that you mentioned and now there's one that uses an electronic eye to see particles in the water as they pass under the boat, using that to calculate speed. I think that if I was to use something other than simple pitot tube speedos, I would go with the GPS because of accuracy and navigation capability.

[sybrmike]

I was thinking the same thing when planning my rebuild, but found some new gauges on the cheap that will allow me to upgrade from pitots to paddlewheel and keep that old school twin speedo theme. Honestly, I haven't needed dead-nuts speed accuracy on a boat in a long time and don't think the kids are going to pick up competition slalom. However, consistant readings are nice from run to run, outing to outing. Only real drawback I found from GPS in a boat are relative surface speeds in cross winds and water currents

I think the NUVI 6 is waterproof, has a boating mode, but comes loaded with street maps only (water maps are big $$$).

[87SunSportMikeyD]

I DO want dead nuts speed control, just because I am very picky about the wake and wave. Speeds counts to me. :)

With that said, JET if you ever upgrade to PP, you will need to replace one old speedo guage with the PP display (which will now display speed, depth, temp, etc I THINK). If you are using a paddlewheel, you should not need your other speedo guage because the paddlewheel will be much more accurate. So if you wanted to pur in the GPS that would be kewl.

The only question I have is what AWESOME gps do you have that is has info for lakes at all??? Mine only shows roads.

[tg0824SSVGG]

Jet,

If I were you - and want PP, I would go with the new GPS-based ones, rather than
the paddlewheel.

I ALWAYS have a GPS on the boat, that I use for speed, not so much navigation .. but it's in a "Ram-mount" - near the dashboard.

Todd

[87SunSportMikeyD]

It baffles me how GPS could be innaccurate on a river. You speed is based on a global position. If the river increases your speed from 23 to 25mph, you are now travelling across the globe at 25mph. How can it not read that? If you turn around, you are now going 21mph across the globe. It's based on how quickly you travel based on global position - 21mph is your real speed of travel across the globe. It's not like it's measuring your engine speedo speeds so where is it getting an incorrect reading.

If I want to go 22 all the time and I am on a river, when I go downstream it should throttle back until 22 is reached on gps. If I turn around and am now driving upstread, it should throttle up untill 22 is reached. Baffled!

If not for everyong saying this, including PP people, I would love to get GPS PP and not drill my boat!

[csuggs]

I think what sybermike is getting at is that the satelites don't know what the current, or flow of a river is at any given time. What matters to a skier or wakeboarder is water speed, not "speed across the globe" as you stated. If you are in the boat on a river that is flowing at 5mph, and you normally wakeboard at 25mph, you would set your speed to be 25mph on the speedo but you would be travelling 30mph or 20mph according to the satelites, depending on which direction you were travelling on the river. So if you set your speed to 25mph with global positioning satelites you could be going through the water at a speed other than 25mph. Right? Or am I thinking too much here. . .:-?

[jet]

OK guys way to technical, lol. no rivers here so I'm good on that one. the gps is a Nuvi 205w (wide screen) $180 last year but I got it for $120! It does show where you've been, creeks, ponds and bodies of water. no depth though.. Don't think I'm getting PP for this boat, Its just to expensive (come on Mikey, can't you make one?) . lol. Im buying!!

i think my question is...is it CHEEZY?

[csuggs]

IMO - not cheezy at all.

[sybrmike]

yeah, what suggs said - boarder/skier's speed across the surface of the water.

Not cheezy - the new boats are going all-digital on the dashes, so why not use a gps speedo as a useful, updated, tool? I'm not gonna keep the points in my distributor just because electronic ignition is "modern"...

[jasonba1]

Hey Jet I like the idea

[87SunSportMikeyD]

"If you are in the boat on a river that is flowing at 5mph, and you normally wakeboard at 25mph, you would set your speed to be 25mph on the speedo but you would be travelling 30mph or 20mph according to the satelites"

But the speed is not set by the speedo, in fact GPS PP should not use a speedo at all. The speedos will function and report speed as they measure it but GPS PP does not use them. The satellite should report your true global speed and adjust the throttle to match. If the you had it set to 25 and the satellite sensed you were travelling at 30 global, it should throttle you back to 25.

However I do see your point about the skier needing water speed not global speed. However I ride on a river EVERY day and I still cannot understand the phenomenom and I would love to...

It makes me think 'why does the paddlewheel work or what does it measure differently??" The only thing I can think is that The boat is not slowed by the full speed of the current. My river is 7mph but when driving upriver I do not have to throttle up that much. The speed is being affected by the additional DRAG on the boat the current causes. Maybe only have to throttle up 2mph when driving upriver. But still, it should adjust to match the speed the satellite is told to watch for.

I guess I can bring my gps on the boat next year and see if the GPS reports speeds that are way whacked off from what the speedos report.

BUT regardless of this phenomenom, I would STILL get the paddlewheel version because it is much cheaper.

[87SunSportMikeyD]

Jet if you like the GPS I would totally use it! You dont HAVE to put it in the dash, though if you are worried about resale value or something.

Okay I have looked into PP quite a bit as far as building my own from parts. In fact I have my cheat sheet right here! If you have a carburated engine we need the older of the two kinds of PP called "Mechanical". It uses a 'servo motor' to control the speed based on the readings from the paddlewheel. The other kind is called DriveByWire or DBW will be printed on the master module and it has no servo motor.

Some parts are easy to find on ebay motors or ski-it-again.com (like dash display guage and master module, other are hard to find like the servo.

You would need:
-Servo motor and parts for mechanical hookup (new from PP $275)
-Paddlewheel (new from PP $129)
-Display (can be single or multiline) ($100 used)
-Master Module (brain or cpu) (cannot say DBW drive by wire, the other kind of PP which is much more common) ($100 used)
-I think there is also a wiring harness of some type that PP would likely need to supply you.

Note that a lot of the PP for sale on ebay motors are incomplete.

So the price for all this listed above is $704 or higher depending if you get used or new parts but it could still be missing some wiring or other needed parts. PP brand new is about $1000. I am still not sure if all that hassle of buying used would be worth the savings. PP will support you GREAT even if you try and build your own.

[csuggs]

Mikey, think of it this way. If you are in the river and it is flowing and you are shut down, then you're drifting with the river. You would not be moving at all relative to the water in the river, but you are moving relative to the land, or satellites. When you power up and drive, your "global" speed is effectied by the current in the river, but your speed relative to the water will be indicated by the speedo.

[sybrmike]

Another way to think of it is the treadmill analogy - the treadmill belt is the river current & you're the boat. While jogging on the treadmill at 5mph, a pitot or paddlwheel speedometer will indicate that you are travelling at 5 mph relative to the speed of the belt (water surface). A hand-held gps will show 0 mph. If you stop jogging, you will travel at the speed of the belt (until you fall off the back). During that time, speedo will show 0 mph and gps will show -5 mph.

[87SunSportMikeyD]

Oooh that was a good analogy. I love a good analogy. I think that got through to me. :) Thanks.

[jet]

Ha..ha..ha...I picture Mikey fallen off the back of the treadmill..LMFAO!! Jet

[csuggs]

Ha..ha..ha...I picture Mikey fallen off the back of the treadmill..LMFAO!! Jet

Yeah, with his GPS in hand . . . . LOL

Sorry Mikey - not laughing at you, just laughing with you!! :D

[jet]

wait..how fast would that be?? 5 mph??

[dshaff24]

Need your opinion?? Last 4th July I took my boat to a new lake that I was not familiar with. So I thought?? Why not take my GPS (I used it in Hawahii on my friends boat) so why not here? I used it while I was there and it was awesome! I ended up trailering the boat after dark every night so I had to go across the lake and the gps showed me where NOT to go and then showed me the line i took the night before so i wouldn't hit any shallow water, logs or dams! lol. So i was thinking..the speedos we have work sometimes and they are old..why not pull them, make a new dash template and snap in a gps?? If i ever get PP it will use a paddle wheel and not the dash speedos..so why not? Cheeezee?? Or not? I think its a great idea, what do you think? Jet We never go out with out our gps, It helps my wife keep me at an accurate speed and our supras old guages are not even close to accurate according to the gps anyway!

Which brings me to ask, Is there a such thing as a digital gps replacement guage? if not then someone should make one as a direct replacment!

[csuggs]

We never go out with out our gps, It helps my wife keep me at an accurate speed and our supras old guages are not even close to accurate according to the gps anyway!

Which brings me to ask, Is there a such thing as a digital gps replacement guage? if not then someone should make one as a direct replacment!

Good question. I gotta believe that someone out there would have a 3-1/4" gauge to fit the location of one the speedos - maybe a multi-function sort of unit.

[mapleleaf]

So if my old speedo's are possibily innaccurate, would a GPS only disapoint me if I learned I really wasn't doing 50mph when the boats empty.....What if it was only 45???
Guess I'll find out this year, planning that pitot replacement that Clint mentioned.....

[87SunSportMikeyD]

You can get new speedos similar to the ones we use now, but the UPGRADE for the airguide speedos would be a paddlewheel speedo like Perfect Pass uses. Replace one dash speedo guage, and the paddlewheel is mounted to the hull after you drill a hole. Should be very accurate. Placement of the paddlewheel is critical.

[jet]

Its wrong..our boats won't go 50 mph. I think top speed back then was like 42ish? Our hulls have to flip and process the water so It can't skim fast across the lake like a new hull. Our hulls would channel the water spin it upside down and spray it out for a great ski wake...thats why I have LWS, its Little Wake Syndrom. It's the only thing I am inadequate on. But without alot of mods i don't think our boats get close to 50 mph. Jet

[csuggs]

Jet -

About 42 is top end on mine. That's the 351W with 1:1 transmission. I think the big-block 454 boats were used for barefooting and had a different ratio in the trans to spin the prop faster. But for most of us, top-end is just over 40. I've found that if the boat is not loaded to heavy and I'm not towing a skier, then the rpms nearly corallate with the speed. Meaning 2500 rpm is equivalent to 25mph and 4000rpm equivalent to 40mph. My friend's '87 Comp is the same way. But when you are towing, it takes about 2200rpm to go 18 or 19mph.

[jzelt]

Same with our I/O. You want a shot to your manhood, GPS the speedo. Boat said 55, really like 42 (matched the RPM's).
With the Supra and it's adjustable speedo, I have calibrated the speedo with the GPS. Didn't take into consideration the current or direction we were heading on the river at the time.

[jzelt]

So to truely calibrate the speedo after re-reading the treadmill analogy (which I fully understand and laughing cause I picture feet slammed against the wall in an awkward position and face being rubbed by tread), I should take the gps reading and subtract-if going downstream/add if going upstream) the current of the river? Then it should be accurate for watersports on the lake or river, right?

[87SunSportMikeyD]

Ya if you have the 1:1.25 tranny I think you could spin it faster, but you would still need a speed prop to make it really humm. No rev limiter though so dont exceed 4500rpm or burnout engine...

Oh and LOL @ treadmill jokes too :)

[docdrs]

I believe that reduces the prop rpm, and allows a bigger prop. bigger is better?

[mapleleaf]

Well it does have the power plus 1:23 tranny....are we hoping for 45 maybe?????come anything more then 42........lol

[csuggs]

A bigger prop with a deeper pitch (more "bite") will increase your speed as long as your motor has the horsepower to turn it. If you're on the edge of your horsepower rating now (like my boat is) then adding a prop with more pitch won't give me any more top end because as it is now I can only get 4200rpm out of the motor. I should be able to get 4400 according to the specs. If I add a bigger prop which requires even more ponies, then my rpms will drop. So be careful changing props. If you go the other way, you could risk over-revving the motor.

[87SunSportMikeyD]

Call JT at NettleProps.com and just chat with him about the best speed prop for your 1:1.23 trans. What is your stock prop Maple?

[dshaff24]

Well it does have the power plus 1:23 tranny....are we hoping for 45 maybe?????come anything more then 42........lol

Haha I know how ya feel!! I went from a speed boat that went 65-67 with ease to maxing out @ 39mph on the gps in the supra! Then Again I got sick of flying around all the time!!

[jet]

I bought the STUMP PULLER prop. 14x14x.105 cup and I have the Power Plus 1:1.23. I had a 13" on it before because some jackass talked me into it, i was at top speed once and looked down and i was bouncing off of 5200 rpm's..NOT GOOD! Id be lucky to hit 32-35 now. Im always in gas saving mode for wakeboarding anyway. Thats why i bought the 14x14 it launches like a flat bottom nitro boat now. I love it. Im just a little worried Im going to spin the motor out of the old stringers. lol. Jet

[87SunSportMikeyD]

Yeah if you have the 1:1.23 and have the room for a 14" 4blade that is the way to go. But if you only have the 1:1 then the biggest prop it can take is a 13"x10.5 3-blade.

[docdrs]

Prop selection is very difficult issue. With cnc manufacturing prop tolerances have been substantially reduced. Thus eliminating problems usu associated with 3 bladed props. Prop blade drag (say that 3x quick) is less in a 3 blade then a 4 blade as there is one less blade . Prop efficiency and cupping also affect performance. efficiency is supposedly maximized around a 1.4- 1.7 pitch to diameter ratio(.74-.8 efficiency), above that and it starts to decline. A .8 ratio results in a .65 efficiency.
We also have to consider that the greater prop spins the more vibration and cavitation will occur reducing efficiency as the forces the prop generates varies from the top of the prop with respect to the bottom due to the angle of thrust in the water compared to the direction of motion.
Cupping will reduce slippage and give you more bite at wot but too much can increase drag.
First you want to stay with in your wot engine range. Then you have to decide whether you want speed or hole shot and with what kind of weight your going to have in your boat. Then you need a bunch of props .
Luckily in a month or 2 Ed G is going to do some of this from the Moomba side.
Although he is looking at mainly wakeboarding props more designed for weighted holeshot apps, than speed and efficiency. he does have a higher ratio prop so it should be interesting how it compares and his standard one compares to these.

[mapleleaf]

Call JT at NettleProps.com and just chat with him about the best speed prop for your 1:1.23 trans. What is your stock prop Maple?

It's under the boat instorage right now! lol I'll have to get over there and take a look, but who's to say it's original? It does need a little repair.....its on my list...... I know it's an OJ, I'll have to look, can't remember the #'s from july!!!! I gotta get something inbetween Mikey, gonna have some weight in the boat this year, it's not a speed boat and I know it, my speedo p/u's are prolly toast, they're on my list too.....50 mph just had a nice ring to it....lol

Any body know the stock prop that would've come on a Conbrio w/351 and a power plus 1:1.23 tranny???

[87SunSportMikeyD]

JT at NettleProps would or else Anthony at Skiers Choice.