Plate length and strut location.

[Snowboat]

On August 26, Lee ss13 responded to a question about wings, and how they affect the boats. I have a Biesemeyer and I measured the plates and the prop distance. I have 1 1/2" inches of plate travel. My plates are stainless and they are 12 inches past the transom. The measurement from the end of the plate to the hub of the prop is 29 1/2" inches. He said his plates are 7" and the prop is 28 inches from prop to end of plate. My boat rides fine when she is hauling ass, starting about 60 mph. There is no porposing at some decent speed. Until that point, I have to pay close attention to the down pedal. There is no up pedal and my speings are tight. When I read Larry's post, it makes it seem that my numbers are way off. Do longer plates create a much higher slip ratio. When I had shorter plates I had trouble keeping it down. Unfortunately, my learning curve has allowed me to drive the boat better and I am wondering if I should have left the plates alone. It runs 95 mph at 4500 feet elevation with Bassett mufflers and 400 rpm higher without. In the fall it will hit 110 on gps. The slip works out to 70% which seems high, but then it is a flat. Are my plates wrong, I plan to increase the HP this winter. I would like to leave the plates and buckles alone, too much money. Whadda does anybody think?

[GofastRacer]

OK, I'll probably make an ass of myself here but what the hay!!.....My plates are 7 1/2 from the transom, never measured the travel but it's enough to control the boat(you rode in it!)..You say it rides fine haulin ass after 60, are you talkin full throttle before 60 or cruisin under 60, if you're just cruisin, you will always have to be down a little on the plate because the boat is not on a set until you stand on it..How is it at 110?, is it a good ride?..You say you had problems keeping it down with shorter plates??, that sounds like plate adjustment or the prop??, have you tried different props??, I think everyone will agree, props can give you nightmares!, I been down that road before!!, did I tell you how much I got in mine???..If the boat rides good at 110 now, leave it alone, you know the saying, "if it works, don't fix it"!!.....Hope this made sense to ya!!!........ :confused:

[V-Drive Tom]

Snowboat, You need to first make sure that you are both measuring your prop location the same way. The correct way is to measure from the TIP of the blade, to the end of the plate.(not the hub) What is your plate location when you are all the out of your down peddle? His propeller is actually further under the boat than yours. By making your plate longer I think you just created a more effective hook in the bottom. That will keep the nose down. But at higher speed will keep the boat more wet,and then start to lift the rear,IF THE PLATE IS DOWN FROM "0" at all. What is you'r main complaint with the boat? Just a little to get the topic started. :) TOM..

[Snowboat]

Hey there Art, making my reservations for next year ant Red Rocks. When cruisin' I use the nine position handle. When it takes a set it is very nice, rock solid. I think I adjusted the plates correctly when they were shorter, but all I could do was shoot the moon until about 5500rpms. Haven't tried different props, need to get to a v drive gathering before I swap some. Playing with gears, jets, timing, etc. before worrying about a prop swap. I am wondering if the long plates increase the drag a lot. Flat out she runs nice and flat, no porpoise, not scary unless you blink, or hit a roller, or the wife punches the right shoulder, for fooling around.

[GofastRacer]

Right on, looking forward to hooking with ya!!..Ok, sounds like you have a problem like I had, a prop that is too viscious,I ran 9's in mine at 7500 at 105, what a pain it was, I could curl the plate under and still pull a wheelie, took some blade area out, went to 18's, WOW, what a difference,sameMPH, better acceleration and a pleasure to drive..I think you need a prop for a K boat???..Tom does make sense!!...What is the distance of your strut to the back of the hull??...This is interesting!!....Damn, got to get up at 2 in the morning, gotta get some sleep, be back tomorrow........ :)

[126driver]

Snowboat, what are you running for a motor right now? That makes a big difference when talking about plate length. My SS boat has 9" plates, and the new K at the shop has 10.5" plates. The struts are located in the same place for both boats.

[Snowboat]

The measurement from the tip of the blade to the end of the plate is 27 1/2". When the foot is off the peddle and the springs are tight the plate is all of 3/8" above neutral. Tom: I know I have too much drag, slip is 70%, off of gps at 91 mph. The ride is great at speed, will run on glass or windy chop, one foot or maybe a little more, much higher speed in chop. The distance from the end of the strut barrel to the end of the plate is 21 to 21 1/2" (too tired and lazy after work to be more precise). 126 Driver: The motor is a Mark 4 460 chevy full roller 700 lift cam, 112 lobe sep. 6/71 at 10% 14 psi boost, dual 750's that work pretty well for now, runs in the 6's well, and has done fine for periods of time in the 7's, rpms not et's. It hasn't been dynoed so it is all bullsh*t. Its healthy, but not spectacular, 91 octane, a little special booster and a little Toluene to make it detonation safer. Planning on a change in the choice of oil I use for next year. I'm sure Shell Rotella 15w-40 is not intended for high rpms at lower engine temps. I will get a manifold with thermostat provisions, this winter, maybe a whipple intercooler and manifold. Time for a little spam for another. When I fixed the motor, when I bought the boat, I reground the Isky cam to their recommendations for the boat. After listening to others, in particular, Superdave, I called Clay Smith Cams. What a treat, he talked to me for a half an hour and it was fun. Gonna get a cam from him for the winter teardown and engine improvement program. I thought the cam I have worked pretty well, but his choice should "wake the motor up", as he puts it. I guess the question is, can I scoot on the back of the boat and plate with what I have , or do I need to change the length of the plates? I want to upgrade the engine a bit, and tweak the prop (Tom), and have a selection of gears for experimentation. I would like to leave the plates alone. The cost to change buckles and plates would be high.

[058]

With that much plate [12" past transom] and 1+" of 'down' Doesn't the boat want to bow-steer when you get on the plate hard? :confused:

[Snowboat]

You know, I think that I don't have enough experience to truly kow what that means. When I nail her it hops twice, takes off and at 60 or 70 I can be off the plate and it is flat and running. Bow steering. Are you saying that it raises the stern too much, driving the bow into the water, creating drag, and wiggling around with out the use of a steering wheel/rudder?

[058]

Too much 'down' makes too much wet area, hull want to go to the right or left without steering it. In my limited experence I have never seen as much downplate as what you have, most plates I've seen has 3/8" to 1/2" total travel. :confused:

[Jetboatguru]

058, we have 2 inches of down in our Comp flat and 2 1/4 in the Abyss. And they both need every bit of it.

[V-Drive Tom]

058, You only need that much down travel to make a race boat take off from a DEAD STOP. The race boats in the older days did not need that much because of, on-plane starts. Propellers changed also.(less diameter and different pitch progression) P.S. I know TONY(JBG) knows this, I just thought I would say it. TOM..

[V-Drive Tom]

Snowboat, If your plate is 3/8 up from 0, and your boat is still tight in the water. I think you are going to be moving your prop forward. If you check with some circle guys with the same bottom. I will bet that their prop is further forward. Because,, If your plate is that far up and your boat is not being carried, then the prop will need to go forward. Before you talk to a guy with the same boat, know your,Prop shaft angle--V-drive placement and motor placement. When you want to talk about a prop, I will help you out with that. TOM..

[Snowboat]

I don't think I have have bow steering, but I'll need to pay close attention, next time out. I can cut the propshaft and go farther forward, but only about 3/8". I'd have to lose a bit of the strut barrel to go any farther forward. I will post the measurements when I get home, tonight. I am wondering if I have the wrong prop. Its a Stellings 11 1/2" by 15 1/2". The ears are not round, but they are not cleavers either, something in between.

[superdave013]

Not to poke my nose in this to much as I don't know squat about roundy round boats. But he's still playing with gear ratios alot also. (29-40) Would having it over or under geared change the way the boat caries the nose? Just something to think about. (My $.02 = not much)

[058]

Jetboatguru, V-drive Tom, Thanks for the info, just goes to show how far behind the times I am. "Ya learn something new every day."

[Sangerboy]

OK I may be having complete brain fade here, but how is it possible that the prop (27 1/2" from the back of the plate) is further forward than the back of the strut barrel (21 to 21 1/2" from the back of the plate) Is it some kind of secret new prop with negative rake? :confused:

[Snowboat]

AAAHHHHHHHHH Sangerboy, I must have been tired and srewed up. Good catch, messed up some subtraction. New numbers are.........back of v drive plate to inside of transom 95 1/2", engine--rear of block to inside of transom is 33 1/4",prop to the end of the plate--27 3/8", rear of strut barrel to out side end of transom 21 1/2", gap between front of prop and rear of strut is 5/8". Prop is 11 1/2" by 15 1/2", not round eared. It is a 10 degreee case and there is no lettering on the strut. I don't know the porpshaft angle. I assume that I need to get a machinist's protactor and measure the angle between the bottom, and the shaft? What do you think? Appreciate any thoughts.

[Flat Screwd]

Snow boat I feel that how far the plates extends past the transom is an irrelevent figure, but rather the distance from the mounting bolts to the end of the plate would be a more comparable measurement. The way I see it is that if your boat lifts out of the water without listing or without much bow rise than your about 90% of perfect.

[GofastRacer]

Hey Ken, you go out and burn some gas today??... http://www.plauder-smilies.com/happy/xyxwave.gif

[Snowboat]

Nope, had to work. I can go in a few days. Hoping for a few more responses so I can be concious of some things to look for, before making any changes.

[GofastRacer]

Snowboat:
Nope, had to work. I can go in a few days. Hoping for a few more responses so I can be concious of some things to look for, before making any changes.You want the measurements off mine??......

[Snowboat]

That would be great!!!!! Thanks.

[GofastRacer]

Ok, I'll measure it all up and send it to ya in a couple of days!......... :)

[Snowboat]

Thanks for the measurements, Gofast. Could I trouble your for one more. What is the distance from the end of the plate to the most rearward point of the prop blade? All of the other measurements, except plate length are within 1/2".

[GofastRacer]

It's 24 7/8, but that's not reliable because our props may not be the same!...If the end of the strut tube is the same distance as mine and the shaft has an inch to the taper, then your prop is in the same location and you're good to go!..... :)