: will raising my motor give me MORE bow lift???


hoytshooter
03-06-2012, 10:22 PM
I need a little more bow lift and was wondering if raising the motor will help this?
1900 pro-v
200 evinrude
21 tempest



Thanks

propmann
03-07-2012, 06:58 AM
I need a little more bow lift and was wondering if raising the motor will help this?
1900 pro-v
200 evinrude
21 tempest



Thanks

Usually it creates bowlift, you may also need to get more tip cupping and or add more rake to your prop to help get more bowlift.

bloodman
03-07-2012, 09:21 AM
The prop and trim create most of the bow lift.

REW
03-07-2012, 02:08 PM
Hoyt,
Just to get a feel for your boats potential performance, you could take every oz of weight out of the bow, and stack it next to the transom for testing.
i.e. move the trolling motor, any bow located batteries, any items stored in bow lockers.

Then, take your boat out to see how it performs.

By moving 3 or 4 hundred lbs from the bow of the boat to the stern of the boat will have a significant effect on the amount of bow lift - with the same engine setting and propeller.

But, this is a no cost, little time effort to see if you like the boats operating character with more bow out of the water.

Propeller rake, motor height, motor position - i.e. on a jack plate or not, all have an effect on bow lift.
(A jack plate can make quite a difference, simply because a jack plate will move a heavy motor further back. By moving the heavy motor further back, it will automatically place less weight in the bow of the boat. )


Good luck
REW

Rich S
03-08-2012, 07:28 AM
REW is right on. There is a saying in the bass boat world that will really hit home on speed and lift.

"100lbs in the back of the boat is the same as 10lbs in the front"

I can tell you for a fact on my boat that is spot on. Before doing anything major get as much weight in the back. Keep the light tackle and life vests etc in the front and try running it again.

From my experience (totally different boat so take it with a grain of salt) lowering the motor will give you more lift. The prop needs to get a good bite to create lift and the higher you go the more disturbed the water is and the less surface area you have on the prop. You also have more leverage lower. Up high the prop just cannot support the lift you are looking for but every set-up is different. That is what is so nice about a Jack Plate. Motor hight is just a simple adjustment. Be sure to keep an eye your psi if you go up.

Also the Tempest is known for lift and of all the props I have used the Tempest won that category hands down.

Phil T
03-08-2012, 11:14 AM
The hull design has a great effect, too. If the OB on my old boat is raised at all, the bow won't stay up. This was with both the main engines that boat has had.

eagle19eye
03-08-2012, 07:31 PM
Your motor's cavitation plate needs to be horizontal or a hair above the hull of your boat. If your motor is raised up a notch you will get cavitation which you do not want. If it is to low you will get a brake effect. Changing the prop is the correct way to help this situation or adjusting weight in your boat. If you change the prop to correct for bow lift you might sacrafice a little top end. The best way is to experiment with different props. Do you have any pics of your current motor position?

REW
03-08-2012, 08:28 PM
Eagle,
I think that a better answer to the height of the motor - is that the motor height depends on the design of the hull.

Certainly you can run the cavitation plate below or even with the bottom of the hull.

But, depending on the design of the hull, you may get much better performance, by lifting the motor higher. You may need to lift the motor from an inch to many inches above the bottom of the transom to get the very best performance from your boat.

In the case of my boat, I find the very best performance, with the cavitation plate 4 inches higher than the bottom of the transom.

So, to be sure; you need to lift, test, lift test, and lift test. Continue testing until you get the best performance from your rig.

REW

eagle19eye
03-08-2012, 10:01 PM
4 inches higher? What size boat and load are you talking about? Just curious. I experimented with mine and anything over 2 from bottom of hull is to much. And even now if I corner really hard I get a little caviatation but I plane great and WOT is spot on.

rabbit
03-09-2012, 01:45 AM
With the tempest prop it says: "Over ventilation-the propeller breaks loose allowing the engine to over-rev before reaching plane (there is to much air being drawn into the propeller blades)
Solution: Decrease ventilation by using a plug with a smaller hole or use a solid plug.
I was thinking maybe you could get more trim if you closed down the holes in the prop too.
Here's the part numbers: Solid plug (19-856622), Large (19-856622 47), medium (19856622 35), small (19-856622 28).....Paul S

Rich S
03-09-2012, 04:25 AM
With the tempest prop it says: "Over ventilation-the propeller breaks loose allowing the engine to over-rev before reaching plane (there is to much air being drawn into the propeller blades)
Solution: Decrease ventilation by using a plug with a smaller hole or use a solid plug.
I was thinking maybe you could get more trim if you closed down the holes in the prop too.
Here's the part numbers: Solid plug (19-856622), Large (19-856622 47), medium (19856622 35), small (19-856622 28).....Paul S

The PVS plugs are just for hole shot and do nothing for top end performance.

staylor
03-09-2012, 06:59 AM
..that works for all boats. Going back to the original post, I would suggest raising the motor for a start if it is sitting flat on the transom- because with a Tempest you will gain some bow lift by getting the prop blades running in aereated surface water as each blade rotates close the the cav plate. This allows the high rake large Tempest blades to provide maximum leverage to lift the bow. In general, it is hard to beat a Tempest for bow lift on an aluminum walleye boat. Note that if this were a high performance bass boat you can actually get the motor running too high- and bow lift will be reduced. By too high on a bass boat I'm talking about being really high- where the prop shaft centerline is an inch or more above the bottom. No aluminum walleye boat could ever run this high. But many aluminum hulls can run with the cav plate 3-4 inches above the bottom with no problems at all if the hull is running at max rated engine power. As for optimum motor height, I'd start with up two holes from flat on the transom, and see if the prop doesn't vent too much for you on turns and in a light cross chop. If the Tempest still bites well running up two holes, then try a third hole, etc. Once you've got the motor height correct, if you need more lift- and can't rebalance the hull by moving stuff to the rear of the boat, then consider having the Tempest reworked- typically by adding some extra tip cup, which will add a bit more. The very tips of the Tempest blades have a thin section about an inch long that appears to be there just begging to be bent a bit if a change in prop lift is needed. In my OMC motor days I'd run the Raker I and SSTRX choppers, which could also be adjusted to add tip cup- but these props had thicker blades at the tips and took a lot of heating and pounding to rework successfully.
Doug

Rich S
03-09-2012, 07:13 AM
I need a little more bow lift and was wondering if raising the motor will help this?
1900 pro-v
200 evinrude
21 tempest



Thanks

One question, how high is your rooster tail at optimum WOT trim? If it is way over your cowling your motor is too high. If there is no rooster tail you are too low.

If you have a lot of steering torque you are too high. If you have none you are on the low side.

If your PVS plugs are set correctly but you get blow out as you are just getting on plane you are too high.

Pezman38
03-09-2012, 08:14 AM
I just raised my engine one hole, I'll let you know soon.

Keep in mind I have a custom blueprinted and balanced prop with enough cupping to pull this off (ihope). This plays a huge roll in how high you can run I am told.

Rich S
03-09-2012, 02:36 PM
I just raised my engine one hole, I'll let you know soon.

Keep in mind I have a custom blueprinted and balanced prop with enough cupping to pull this off (ihope). This plays a huge roll in how high you can run I am told.

Watch your PSI as you trim. It can drop real fast and can cause big problems if you are too high.