why wont it go FASTER!!!

[fisherguy123]

Re: why wont it go FASTER!!!

have you tried switching motors with your buddy to see the results.....if his motor shoves your boat faster then its your motor holding you back and you have a place to start looking for some answers !

 

[mommicked]

Re: why wont it go FASTER!!!

Whats the HP of your buddies motor? You did'nt say. Could he have a 18 or 20 in sheeps clothing?, or a bored out, rebuilt 15 that's now more than 15hp? Whats the diff. in the 2 motors weights and prop sizes? I'm guessing your boat is also slightly wider than the other boat.

 

[all duck'd up]

Re: why wont it go FASTER!!!

He means out on the tilt pin. Probably position 3 of 5 will yield a couple mph, but you can try them all.

If you've painted the hull, it will cost a ~couple mph.

That is a very common prop, if you're thinking new, iboats has new Solas Amita's for $55 that will outperform the stock BRP and of course the $117 Solas stainless that will add even more performance.

In simple terms a 4 blade prop will lose a little top end, but decrease minimum planing speed and lift the stern a bit.

From the factory, your motor should be making a little more power than your buddies.

i dont see how the paint will slow me down that much is clean and almost like factory; and it needed a few coats (the boat was ruff when i 1st got it)

im going to pull the prop today to see which one i have.

 

[all duck'd up]

Re: why wont it go FASTER!!!

It appears the plate is at least an inch below the bottom. You can raise the motor by just using a stick on top of the transom to hold it up while you tighten the clamps just be sure the clamps have a good grip.You may be able to gain an inch or so.
If the mount has bolt holes you could use them to get it higher if necessary. A jack plate would be ideal to fine tune the height.
I usually suggest raising the motor to a point just before venting becomes a problem.In the extreme you could gain a couple of mph just by raising the motor.
Your friends motor is rated at the power head; thus his actual hp is about 5-10% lower than your prop rated motor.
All the more reason you should be faster when set up right. How many keels does your boat have? Some jon boats have 5 or more keels.these tend to slow the boat. Do we know the size of your prop?

i was thinking about putting a 1/2 inch or 1 inch pease of wood on top of the transom to lift it some. the top of my mount has a notch in it and i can fit something in it very snug

it also has a bolt hole, but i want to make sure i have it at the right hight before i start drilling holes in my rig

here is what i was thinking about


it has 3 keels

 

[all duck'd up]

Re: why wont it go FASTER!!!

have you tried switching motors with your buddy to see the results.....if his motor shoves your boat faster then its your motor holding you back and you have a place to start looking for some answers !

really dont think he will go for that and plus everyone is saying its a transom hight problem so i will probably be in the same boat <<< haha see what i did there lol

 

[all duck'd up]

Re: why wont it go FASTER!!!

Whats the HP of your buddies motor? You did'nt say. Could he have a 18 or 20 in sheeps clothing?, or a bored out, rebuilt 15 that's now more than 15hp? Whats the diff. in the 2 motors weights and prop sizes? I'm guessing your boat is also slightly wider than the other boat.

his is a stock 78 erude 15hp with a what he said was a newer modle prop; but im almost sure all the props are interchangeable from 1974 to 2005 on the 2 strokes. so i think he just changed the pitch. other than that the motor sat in a barn for about 15 years until his grandfather passed and his dad gave it to him.

 

[all duck'd up]

Re: why wont it go FASTER!!!

why did my page move under the (Prop Questions and Topics) thread??? i started it in the johnson/erude page.

 

[dazk14]

Re: why wont it go FASTER!!!

Trim angle will yield the quickest/easiest path for speed - then play with heights. At 19 mph -you're not going have much lower unit drag.

Hull drag with pin in lowest position = significant.

Your trim angle - visually - looks pretty good, however I'm presuming you are using a "Trailering bracket" - correct?

A bottom hull level from side with engine locked onto the bottom pin, is always helpful.

At this point, the conversation has focused on prop/setup issues - so you'll get more bites under this forum heading.

 

[all duck'd up]

Re: why wont it go FASTER!!!

Trim angle will yield the quickest/easiest path for speed - then play with heights. At 19 mph -you're not going have much lower unit drag.

Hull drag with pin in lowest position = significant.

Your trim angle - visually - looks pretty good, however I'm presuming you are using a "Trailering bracket" - correct?

A bottom hull level from side with engine locked onto the bottom pin, is always helpful.

At this point, the conversation has focused on prop/setup issues - so you'll get more bites under this forum heading.

1. no I'm not using a trailering bracket.

2. I will try and snap a level pic from the side tonight when I get off. Iguess ill try to take a few different ones with the tilt pin in each hole and see which you think would be the best.

 

[smokeonthewater]

Re: why wont it go FASTER!!!

forget the pics, just take it out and RUN it in the different trim settings... nobody can tell where to trim it from a pic
Try it for a minute, shut it off, tilt the engine and (don't drop it) move the pin, put the engine down, fire it up and go..... repeat as needed to find best trim..... changing number of people in boat and changing water conditions will warrant potentially changing trim

 

[all duck'd up]

Re: why wont it go FASTER!!!

no pin

pin in 1st hole

pin in 2nd

and 3rd


the rest just looked stupid crazy

 

[steelespike]

Re: why wont it go FASTER!!!

The only way to get the best trim seretting is to test run it at each setting.It will become obvious which setting does best.
It does appear the plate is below the bottom and sometimes you can raise it to about an inch above. could be almopst 2" better.
Probably not a huge speed difference but could be.Raising the motor can also improve hole shot and may reduce porpoising slightly.
I did a little research and found the 78 and 04 have the same gear ratio but the 78 is rated at 7,000 rpm the 04 6000.
Assuming the motors could turn the 3 commopn props to their max rpm the 78 has a big edge a 10" on the 04 does about 21.8 at 6000, the 78 does about 25.5 at 7000. A 9" prop the 04 does 19.7 @ 6000 the 78 22.9 @7000.Both motors are more likely to reach max rpm with a 9" than a 10" or of course the 11"I think you can see if your running a 9" and he a 10 That likely he could be faster regardless of the rpm.
My info is limited so you may be able to check with a well established dealer what the 04 is rated at for sure.

 

[all duck'd up]

Re: why wont it go FASTER!!!

thanks for the great info guys

i will be testing it out this weekend and post what happens

 

[smokeonthewater]

Re: why wont it go FASTER!!!

The only way to get the best trim seretting is to test run it at each setting.It will become obvious which setting does best.
It does appear the plate is below the bottom and sometimes you can raise it to about an inch above. could be almopst 2" better.
Probably not a huge speed difference but could be.Raising the motor can also improve hole shot and may reduce porpoising slightly.
I did a little research and found the 78 and 04 have the same gear ratio but the 78 is rated at 7,000 rpm the 04 6000.
Assuming the motors could turn the 3 commopn props to their max rpm the 78 has a big edge a 10" on the 04 does about 21.8 at 6000, the 78 does about 25.5 at 7000. A 9" prop the 04 does 19.7 @ 6000 the 78 22.9 @7000.Both motors are more likely to reach max rpm with a 9" than a 10" or of course the 11"I think you can see if your running a 9" and he a 10 That likely he could be faster regardless of the rpm.
My info is limited so you may be able to check with a well established dealer what the 04 is rated at for sure.

Actually the 04 has the advantage..... same horsepower at lower rpm = less drag.... likely they would each reach peak with different props IE 9" on the 78 at 7k rpm and 10" on the 04 at 6k rpm

Then the 04 has a second advantage mentioned earlier of having about 15% more HP being rated at the prop 'stead of the crank.

 

[dazk14]

Re: why wont it go FASTER!!!

no pin
View attachment 128388
pin in 1st hole
View attachment 128389
pin in 2nd
View attachment 128390
and 3rd
View attachment 128391

the rest just looked stupid crazy

Excellent job with the pics! Plainly obvious what's going on here.

You have the shallow water drive (tilt-out a bit) bracket engaged (also popular when trailering).

The last picture shows it best, its the rusted U shape bracket connected to the mid-section and resting on the tilt pin.

This needs to swing up out of the way, then your motor will trim all the way in and engage the tilt pin correctly.

That is why I said the original trim position looked pretty good from a performance point of view.

From the picture in the lowest trim position, I agree with Steelespike, The L/U is dunked in fairly deep. Raising it up a bit should help the characteristics Steele mentioned.

My suggestion is start safe 3/4-1". The higher you go the more concern with aerated cooling water that can cause an overheat.

So, the question remains, are you racing your buddy with the shallow water bracket engaged?

 

[all duck'd up]

Re: why wont it go FASTER!!!

Excellent job with the pics! Plainly obvious what's going on here.

You have the shallow water drive (tilt-out a bit) bracket engaged (also popular when trailering).

The last picture shows it best, its the rusted U shape bracket connected to the mid-section and resting on the tilt pin.

This needs to swing up out of the way, then your motor will trim all the way in and engage the tilt pin correctly.

That is why I said the original trim position looked pretty good from a performance point of view.

From the picture in the lowest trim position, I agree with Steelespike, The L/U is dunked in fairly deep. Raising it up a bit should help the characteristics Steele mentioned.

My suggestion is start safe 3/4-1". The higher you go the more concern with aerated cooling water that can cause an overheat.

So, the question remains, are you racing your buddy with the shallow water bracket engaged?

i thought that was funny looking when i was messing with it yesterday. it is stuck like that from rust. i will try and free it up today, now that i know it should be able to move

wd40 and a hammer yay! :facepalm:

 

[waterinthefuel]

Re: why wont it go FASTER!!!

Whoa, there sure is a lot of information in this thread, and unfortunately a lot of MISinformation.

First of all, 93 octane will do NOTHING if your engine is not specifically set up to run on it. In fact, since 93 is a slower burning fuel the engine could run worse. It will be specifically labeled as "premium fuel only" if it needs it. Otherwise, stick to the 87.

Number two: premium fuel is NOT cleaner and does not have more cleaning additives in it!! Gov't regulations require that all fuel be the same amount of "clean", octane is simply a resistance to detonation. Chevron, for instance, puts Techron in their fuel. They put it in ALL grades, not just premium.

Number three: Lose weight. Work out several times a day. This will help you out run him. And once you beat him, when you're in shape, you'll be beating off the women back at the dock who want to have a little rendezvous with the winner if you know what I mean.

OK so number 3 might be stretching it but one and two are accurate.

 

[all duck'd up]

Re: why wont it go FASTER!!!

yeah i think we are past the octane debate

and thanks for the self esteem boost

 

[smokeonthewater]

Re: why wont it go FASTER!!!

good catch on the bracket DAZ..... I sometimes forget that not everyone was born with the ability to just look at a machine or mechanism and just figure it out..... Plus I never had an outboard with one of those....

ducked.... now you can get that thing out of the way and play with the trim like I said above.... Be careful with the hammer tho.... DAZ, is there a release or something or is it simply under spring tension?

 

[impatico]

Re: why wont it go FASTER!!!

Whoa, there sure is a lot of information in this thread, and unfortunately a lot of MISinformation.

First of all, 93 octane will do NOTHING if your engine is not specifically set up to run on it. In fact, since 93 is a slower burning fuel the engine could run worse. It will be specifically labeled as "premium fuel only" if it needs it. Otherwise, stick to the 87.

Number two: premium fuel is NOT cleaner and does not have more cleaning additives in it!! Gov't regulations require that all fuel be the same amount of "clean", octane is simply a resistance to detonation. Chevron, for instance, puts Techron in their fuel. They put it in ALL grades, not just premium.

Number three: Lose weight. Work out several times a day. This will help you out run him. And once you beat him, when you're in shape, you'll be beating off the women back at the dock who want to have a little rendezvous with the winner if you know what I mean.

OK so number 3 might be stretching it but one and two are accurate.

Up here in Canada unless it's marked IE purple premium the premium fuels DO have more cleaner agents. Chevron premium has 3X more cleaners in it than the regular 87