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| I HAVE A 1996 RANGER 690VS WITH A MERC 175 EFI. TOP SPEED IS 52 FULLY LOADED. WOT IS MAXED OUT. I NEED MORE OUT OF THE HOLE. I AM WILLING TO LOSE SOME TOP END. I AM RUNNING A TEMPEST 21 PITCH PROP IN GREAT SHAPE AND ALL THE VENT HOLES ARE OPEN. ANYBODY RECOMMEND A DIFFERENT PROP. |
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| I SHOULD ADD THAT ANYTHING UNDER 35 MPH IT FIGHTS TO STAY ON PLANE. EVEN WITH THE MOTOR TUCKED ALL THE WAY DOWN. BOAT WONT EVEN CONSIDER DOING 25-30 MPH. |
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Location: Hayward ,Wisconsin | I have the same 175 merc. with a Trophy Plus 4 blade ss 23 pitch works great for the DC 18' Tundra.
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Posts: 42
| I have a 1998 690vs with the 175merc and I am running a custom merc tempest plus FOUR blade 23 pitch from D.A.H. props and I have no problems getting out of the hole and top speed of 62mph gps at 5900 rpm. Telephone number is 262-534-4440 ask for John and he will set you up with a prop. They are in Burlington WI. |
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Posts: 17
| I also run a '96 690vs. It has a High Five Prop on it. DO NOT go with this prop. Slow out of hole and 52mph with low fuel and only 1 person. Is the tank 48 Gallons on this boat? |
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Posts: 42
| What pitch high five? I am running a 19, great out of the hole, but only 50 mph gps. The 23 DAH 4 blade sounds like the best, but cost? |
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| my 96 has a 42 gallon up from and a 8 in the back. |
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Posts: 332
Location: Neenah, WI | I have a 94 690 with a merc 175 ,I have used a high five 25 great hole shot top end speed 52 , a tempest 21 3 blade fair hole shot top end 57, I finally settled on a laser II merc prop 3 blade 21 pitch great hole shot and good top end speed 61 mph .
SAint |
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Posts: 17
| 23 Pitch. Was told the cup was out and my local Ranger dealer sent the prop to Indy ro be rebuilt. $230 later and no better, If I had known this I would have replaced the prop. |
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Posts: 176
Location: Tomahawk, WI | To all 690 owners with 175hp,
Are your boats poposing at 4000 and lower rpms, i have a 98' 690 with 09' 175 Optimax running a 21 pitch Tempest Plus, great hole shot and top end but mid range cruising 4000 rpm (gas saving mode) it porposes badly even with fully trimmed down. Maybe jack plate is the answer. |
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Posts: 3508
Location: Elk River, Minnesota | Hiya,
Have you tried changing the hole size for your vents to a smaller hole? What could be happening is you are getting some exhaust coming out the vent holes at the lower RPMs, causing some ventilation of the blades. When this happens, you lose grip on the water, and thus the prop cannot hold the bow up, thus the porpoising. The issue with a vented prop is that at lower speeds, the vents allow exhaust into the fins and you cannot keep it on plane....that is normal. So...when you run a vented prop, you must maintain a certain speed to keep the boat on top of the water. Not always the most efficient system to have, and if you get into a wind where you need the extra thrust but not able to run on plane, a vented prop can be a nightmare.
I am also wondering on your max RPM's for the motor and what are you getting for max RPM's for your normal load. If you are low on max RPM's, then I would say you are over-pitched a touch and the motor in it's mid-range power cannot keep the bow up at any trim angle.
I would start with the vent plugs and see what happens there. Go to a smaller hole for each vent and try out the prop...you might be pleasantly surprised. It is an easy thing to do and not all that expensive.
Steve
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Posts: 176
Location: Tomahawk, WI | Steve, now that you mention it, on the three prop vents one is missing! I should order a new set, i dont know right now witch size i have in on the remaining two but i will check tonight. I can spin the prop at 5900 RPM right now with max speed of 54 with two people and a 4 stroke kicker motor and all our musky gear so i dont think im over pitched. Thanks for your help and i will order a new set of vents. What size would you recommend ? 3/8.
The porposing is at its worst when running into the wind with a 6"-1' chop. I get on plane and back off to 4000 rpm's with the motor fully down and everything is fine for about 5 seconds and then its starts to porpose and continually gets worse untill i give it more throttle than it will sooth out.
Edited by PANTLEGGER 8/1/2011 9:45 AM
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Posts: 13688
Location: minocqua, wi. | great information ... thank you steve! |
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Posts: 32935
Location: Rhinelander, Wisconsin | One reason that boat porpoises at that speed is weight distribution and the lift at that rpm to the pad. The boat is trying to lift to the pad, but can't quite get it done and literally falls off again, causing the boat to 'bounce'. At about 3800 to 4000, the engine needs to be trimmed down. One way to fix the issue is a TH Marine 5 degree motor wedge, giving you 5 degrees more negative tuck. Another is to try a Rev 4 prop which may give you enough lift to power through the porpoise trimmed down, and no 'bounce' will be noticed.
The vented prop allows for gasses to escape quickly giving you a better hole shot, and with engine height correct should be sealed up by water flow.
http://www.mercurymarine.com/propellers/advantage/technologies/pvs/ |
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Posts: 176
Location: Tomahawk, WI | glog and saint, you guys are getting over 60 mph on a 690, that is crazy fast for a deep v fiberglass hull |
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Posts: 13688
Location: minocqua, wi. | PANTLEGGER - 8/1/2011 11:30 AM
glog and saint, you guys are getting over 60 mph on a 690, that is crazy fast for a deep v fiberglass hull
i could see the later vs hulls getting nominally faster. i've got a '94 too and can't see it going anywhere near 60 with any prop. 52 is realistic and i've heard 54 but i don't buy 60's either. |
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| jonnysled - 8/1/2011 11:56 AM
PANTLEGGER - 8/1/2011 11:30 AM
glog and saint, you guys are getting over 60 mph on a 690, that is crazy fast for a deep v fiberglass hull
i could see the later vs hulls getting nominally faster. i've got a '94 too and can't see it going anywhere near 60 with any prop. 52 is realistic and i've heard 54 but i don't buy 60's either.
I had a 96 that topped out at 61mph. It was under the right conditions...
Could do low to mid 50's all day with two guys and a full load of gear.
The gas bill in either scenario was no fun... |
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Posts: 13688
Location: minocqua, wi. | buy it - 8/1/2011 12:01 PM
jonnysled - 8/1/2011 11:56 AM
PANTLEGGER - 8/1/2011 11:30 AM
glog and saint, you guys are getting over 60 mph on a 690, that is crazy fast for a deep v fiberglass hull
i could see the later vs hulls getting nominally faster. i've got a '94 too and can't see it going anywhere near 60 with any prop. 52 is realistic and i've heard 54 but i don't buy 60's either.
I had a 96 that topped out at 61mph. It was under the right conditions...
Could do low to mid 50's all day with two guys and a full load of gear.
The gas bill in either scenario was no fun...
the '94 is almost a rectangle ... or so it seems. didn't the hull change design in '96?? |
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Posts: 176
Location: Tomahawk, WI | Just called the local shop and they have the vents in smaller size $2.08 each. I will try that. Thanks steve. |
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Posts: 13688
Location: minocqua, wi. | let us know what you find out pantlegger ... |
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Posts: 42
| That is the reason why I tell people to go see John at D.A.H. props. They custom make your prop to the horsepower and boat weight. I have seen other merc. props that are four blades and with a 23 pitch and they look nothing like I have. If you don"t belive the speed come on down and I will take you for a ride and then you will be a beliver. On certain days I have had this rig going 64, it seems strange but I think it has to do with water temp and air temp. I have two gps in the boat and they are within a 1/2 mile per hour differance. |
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Posts: 13688
Location: minocqua, wi. | where is D.A.H props located ... i never, ever thought it would even be an option to get that kind of performance out of this boat just by propping it. |
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Posts: 42
| Burlington, WI 262-534-4440 |
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Posts: 32935
Location: Rhinelander, Wisconsin | -------------------------------
One reason that boat porpoises at that speed is weight distribution and the lift at that rpm to the pad. The boat is trying to lift to the pad, but can't quite get it done and literally falls off again, causing the boat to 'bounce'. At about 3800 to 4000, the engine needs to be trimmed down. One way to fix the issue is a TH Marine 5 degree motor wedge, giving you 5 degrees more negative tuck. Another is to try a Rev 4 prop which may give you enough lift to power through the porpoise trimmed down, and no 'bounce' will be noticed.
The vented prop allows for gasses to escape quickly giving you a better hole shot, and with engine height correct should be sealed up by water flow.
http://www.mercurymarine.com/propellers/advantage/technologies/pvs/
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Take a look at that link. According to Merc, the time the vents come into play is powering up by allowing exhaust gasses to flow over the outside of the prop increasing RPMs and shortening hole shot; once you are underway, the vents are sealed by head pressure with water flowing across the hub.
Three blades are way faster than 4, so a 3 blade prop will offer a better top end and slower hole shot. Advanced designs like the Rev 4 offer more 'lift' that allows the hull to have less wetted surface and therefore better top end despite the fact you are spinning four blades. With that also comes better ability to keep the nose of the boat down while the boat is coming onto the pad, which is in that 4000 rpm range. The rev 4 is an ideal wheel for big walleye boats like the 690, 620, and 621.
64 is danged fast for that boat running a stock 175 and standard load.
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| Ok, first I want to apolgize for being a dork and not understanding this prop stuff. Reading all the posts I am more confused what I should do.
I just checked my Prop..Tempest Plus 21 pitch. I have 3 plugs with about a half inch hole in them that are actually ovaled out from wear. Boat porpoises at 35-40. Battles to stay on plane from 25-30. 52 mph top end loaded down. Dog out of the hole. What is everybody suggesting I do? |
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Posts: 3508
Location: Elk River, Minnesota | Hi Jim,
What kind of RPM's are you seeing at wide open throttle? I would be curious of what that number is as you mention it is a dog out of the hole.... without any other information, I would suspect you might be high on pitch and/or too large on diameter.
As you can see on here, there are many different variables that can come into play when setting up your rig, and propping the boat correctly is THE piece of the puzzle you have the most options to play with as far as set-up of your rig.
If you would, I would say let's start at your wide open throttle rpms and work from there... I'll work with you on it.
Steve |
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Posts: 42
| Jim,
Did you just buy this rig or have you had this problem from start? What hole is the motor mounted to the boat, count from the top hole? Mine is the fifth hole from the top. I have had no porpose problems at that speed or rpm, fully loaded or empty.Do you have the TRIM TAB STILL ON THE MOTOR? Is this problem with a full tank of gas or does it porpose with a half tank, quarter tank? I am going to have to disagree that a three blade prop is better than a four. A four blade is going to get you out of the hole faster and have more top end and control factor at top speed. Think about it, you are always going to have another blade in the water to give you more push and torque. If a three blade is better than why do they run four blade props on a mastercraft and run the same in race boats? People comlain about the four blade props because of there price until they own one.
Edited by glog 8/1/2011 8:09 PM
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Posts: 32935
Location: Rhinelander, Wisconsin | Who said a three blade was 'better'?
A three blade prop in the same diameter and pitch (and basic design) will be faster than a four. Sorry, that's just the physics of the machine.
The trim tab is designed to adjust for torque, not porpoise.
How many open holes do you have above the top bolts, g? |
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Posts: 13688
Location: minocqua, wi. | i porpose with a 4 blade tempest (not sure the pitch) and i believe when i'm less than half a tank. i'm not at home but will gladly be a part of this test. i get home friday and will collect the numbers and hopefully help my own situation and help others with the same thing going on. just seeing that it's a common thing and that there are options is good. |
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Posts: 42
| There are four open holes and the bolt is in the fifth. Steve then why when I put on my spare prop which is a mercury tempest plus three blade 23 pitch I lose 6mph at top end and it takes longer to get the boat onto plane????? Just stating about trim tab because you do not need it on there if you have hydralic steer.
Edited by glog 8/1/2011 8:52 PM
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