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Posts: 238
Location: Rhinelander | A lot of guys have been great with the helpful tips, well please try and shorten my search for a new prop.
"New" rig this year is a '95 Ranger 690vs with a '95 Merc 175 efi. Original owner had a 23P 3 blade Tempest and the more I run this it just doesn't seem the like ideal setup.
To much throttle out of the hole and the RPM's spin out past 6000 real fast with the boat not wanting to plane. I would prefer a quicker holeshot and really don't care about top end speed. Couple of mph's here and there is no big deal to me. Taking what seems like forever to plane this boat is turning into a pain.
I'm guessing 4 blade, but what pitch and name? |
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Posts: 208
Location: Sun Prairie, WI | Can you get the boat on plane? If not, you may have a spun hub in the prop. A local prop repair shop should be able to replace the hub, If you can get on plane then most likey need to go to a higher pitch prop. Currently running a 23 I would try a 25p or possibly a 27p I used to work for a prop repair place near madison and I think it was something like 200rpm per inch of pitch that is lost or gained my going up or down in pitch, Good luck. ps I cant remember what the rules were when switching from a 3 blade to a 4 blade. |
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Posts: 3508
Location: Elk River, Minnesota | Hiya,
First question: On that tempest prop, are there holes on the main portion of the hub right at the bottom of the fins? If so, that would explain the high RPMs without anything happening. Chance are you can get different plugs that adjust the hole size to set up your motor the way you would like it.
Next, where is the motor mounted on the boat in relation to the transom? Is it tight to the transom? Up a few holes? Setback plate? All of those things can affect how the boat performs both at top end and at hole shot. If the motor is too high, the prop will just spin easily without grabbing water. Trim angle can come into play with this as well...if the motor is not trimmed down as much as it could, it may essentially allow the prop to break loose.
As was mentioned as well, if the motor is mounted using the designed bolt holes on the motor without a jack plate (setback plate), the potential of having a spun hub is definitely a possibility. A spun hub will usually show up at hole shot, but it will also show up under high load (midrange throttle as well). If you get the boat up on plane, back it off just a touch to where the motor is really working to get the boat up....if it has trouble there and spins higher RPMs, a spun hub is looking more probable.
That tempest prop is a good prop. Lots of cupping so it should grab well at all trim angles. If you have access to a prop shop, bring the prop in and see if they will take a look at it. The pitch you have should be pretty close to what you will need, and if memory serves me correctly, that motor will have normal WOT at 5500 or so.
If you have a buddy who has a similar sized motor, see if you can borrow a prop of the same pitch (even aluminum) and see if the same thing happens. If so, then I'm betting it's not a spun prop...
I'll try and keep in touch if you'd like...I love this kind of "tinkering" to get the most out of the boat. That rig overall is a solid rig too... I've considered looking into a 692...
Steve |
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Posts: 238
Location: Rhinelander | Thanks for the quick responses. Might and very well could be a spun prop.
Existing prop (Tempest) does have the holes, motor is trimmed all the way down and no jack plate.
Today was family fishing day and with two more people in the boat really struggled to plane, I had to cut sharp turns to get her up on plane without screaming to many RPM's . Slow throttle back bringing boat off plane; was another tricky throttle work and wheel turns to bring her back up.
Knew something wasn't right, never had a spun prop before and I guess this is my issue. Hopefully not too costly.
Thanks again for the help and I'll keep updating until the problem is solved. |
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Posts: 202
Location: Rhinelander | Hodag, I would take it out to Jim at Duke's Outboards. Even though its a Mercury he is very knowledgable and helpful on issues like this, and reasonable! There is a lot of great info posted here, but he can actually see what you have, ask a few questions and probably test for a spun hub.
Edited by hodaghawg 5/31/2009 7:37 AM
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Posts: 3508
Location: Elk River, Minnesota | Getting a prop re-hubbed is not very costly...much more of a cost savings to get that done rather than getting a whole new prop. It's a good starting point for the issue you mention... a spun hub will not spin easy, like a stripped thread on a bolt, but it will give under a good load.
Any good prop shop/dealer will be able to put the prop under load and see what is going on...
Steve |
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Posts: 238
Location: Rhinelander | Ok, the prop will be brought in Monday and assuming it is spun, I have to guess it's at least a $100 dollar bill to repair. Is the Tempest 3 blade 23P the "right" prop for this set up? Looking at used props most are between $250-$350. I have a few "high fives" for sale in my area......I guess I'm still looking for insight, Steve(VMS) have anymore pointers?
I'd rather spend a little more up front if what I really need is a differant prop to obtain a good hole shot and boat control. Again top speed is not a concern as long the rig is still in the low 50's.
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Posts: 3508
Location: Elk River, Minnesota | With that rig, I would doubt you would need a 5 blade prop. You'd get great handling with it, but a high 5 is not going to be a very fast prop by any means. I would guess that the 23 pitch you have will do well, although once it's been checked and rehubbed if needed, that will be the telltale sign.
Once you get it out after having the prop checked, see if you can obtain the following items: RPM's at WOT at best trim, GPS speed at WOT, the max RPM's the motor is recommended to have, and the Gear ratio of the motor and the motor mounting height (bolt hole #1 being lowest mounted position tight to transom and numbering up from there). With those numbers getting "dialed in" will be much easier to do.
I'll work with you on it...
Steve |
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Posts: 42
| I have a 98 ranger 690vs with a 98 merc 175efi and this has a four blade 23p stainless prop on it. I would have to say that this is a good running prop. Good out of the hole and excellent top end. You might want to give that a try. |
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Posts: 238
Location: Rhinelander | Ran a 23P Merc Alum prop last night. Max RPM's hit just over 6000 on the tach, GPS speed was a touch over 50mph but I was running out of lake......could be slightly more.
The old efi has a max of 5600 rpms...23P may not be the right set up. The vent holes in the Tempest prop, which was on the boat at purchase, must need the plastic inserts to even run half way decant.
I'm hesitant to even stick with the 23P SS Tempest.....Plastic inserts are an order item and this may not even be the direction to head.
We're trying somthing different tonight, just don't quite know what yet. Note: Buddy owns a large dealership but does not sell fiberglass boats and engines top out about 150 hp. He is very knowleable but other ideas and pointers always welcome. |
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| If you have no inserts in the vent holes, that is most likely your problem. Good Merc dealers will stock these in Small, Medium and Large hole size. They only cost about $6-8.00 per pack. I'd suggest trying the medium plugs, and see how your hole shot is. If you are still spinning the motor up too fast, go to the smaller plug. Also, if you spun the hub, that prop should have the Flow-Torque hub in it, and you can replace that yourself easily. Ask your dealer for the proper torque spec on tightening the hub nut.
If you were getting over 5600 with the aluminum prop, I could see the 23P Tempesrt as a good prop for you. They will bite harder than the aluminum prop, and won't deflect, and should bring your RPM's down to an acceptable range. |
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Posts: 238
Location: Rhinelander | Prop isn't spun and from what I understand the hub is the older "rubber style" not the new plastic hub insert. From what we're looking at this is an older Tempset prop, his plastic inserts didn't fit.
Shouldn't the inserts be the same for all Tempest props? Is the Tempest Plus a different prop? Mine only has Tempest on the side, with this part number 48-825864 A40 23P
Starting to miss the old reliable Fishhawk........... |
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Posts: 3508
Location: Elk River, Minnesota | Without any vent plugs in, that would explain the high RPM's and no forward thrust. Getting something in those holes will greatly increase your thrust overall. If you went over your max rpms with an aluminum, you will be very close to the sweet spot on that tempest...
Get the plugs in and I bet you will be a much happier camper.. Frustrating to say the least when you buy a different rig and things are not quite what they should be. Any chance to get a hold of the former owner to see if he has the plugs?
Steve |
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Posts: 2384
Location: On the X that marks the mucky spot | I'm guessing the motor's too high. You can't get on plane and you're over-reving the engine. The 23 should be the right size for that rig. The only exception is if the guy before you had the prop reworked. Most shops can't fix a Tempest worth a darn. Many will just grind them down and leave the cup out. This could explain the issues you're having.
Report back which holes your motor is mounted on and take a look at the prop. There should be quite a bit of cup or lip on the tips of the blades. Those are the 2 problems I can see.
BTW, what was your max speed with the Tempest?
Edited by Muskie Treats 6/2/2009 12:09 PM
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Posts: 734
Location: Watertown, MN | Get the vents in and try that first, if still same problems I would go for the REV 4 23P(find a dealer where you can test them) will give you a better whole shot and rought the same top end. I believe the vent will take care of one of your issues, if everything else is setup correctly. Lack of hole shot is because of spinning to big of pitch, and over RPM is cause by spinning to low of pitch.
Troyz |
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Posts: 238
Location: Rhinelander | Here is the motor mounting location on the boat.
With the alum prop last night I did lose "traction" when corneing on full trim. I just assumed this normal and trimmed down to accomadate. Maybe not?
http://i361.photobucket.com/albums/oo54/hodag2hunter/IMG00060.jpg
http://i361.photobucket.com/albums/oo54/hodag2hunter/IMG00059.jpg
Edited by Hodag Hunter 6/2/2009 1:42 PM
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Posts: 2384
Location: On the X that marks the mucky spot | One thought. If it's an older rubber hubbed tempest then it won't have the hole plugs. Your model had the old holes, not the ones that could take the plugs.
I'd drop the motor down one hole.
Yes you can lose traction at full trim, but you shouldn't if your set-up is dialed. |
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Posts: 42
| You need to forget about a aluminum prop. Stick with the stainless. My 98 merc 175efi is set at the fifth hole down from the top of the adjustment holes witch means the motor is all the way up. I am running 6100 rpm and GPS speed reads 59 mph. I do not have any problems getting this rig on plane. This prop is a DAH 23PITCH FOUR BLADE WITH THE VENT PLUGS OPEN, it is made in Wisconsin and they can custom make you a prop for the same price as a tempest or any of the other brand props. |
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