1994 40HP evinrude on 13' inflatable

[DGartzos]

Performance: balanced, leaning toward top speed
current blade: 11 3/4, 17" aluminum
boat: 13' inflatable Lomac (italian) with hard shallow V keel
motor: '94 40HP envinrude
speed: 30 Knots GPS
revs: 6800 WOT two persons onboard

Motor new had a 15 pitch blade (cannot remember diameter). Scraped blade and got this 11 3/4 17" which looked smaller than original but mechanic suggested it would suite more. Boat lost at least 5-6 Knots top end speed but having wrong setting on tach did not think of blade but tried wider throat carbs. Boat has thrusts of power, response to throttle is absolutely immediate and since correct tach setting WOT rpm is 6800 and not 5700 believed before.

It is impossible to try different blades in order to decide.

What blade should i go for?

 

[hwsiii]

Re: 1994 40HP evinrude on 13' inflatable

D, welcome to Iboats prop forum and we will try to help you as much as we can but without more information no one can help you, and I will tell you I need more information than anyone else. But if you would like my help fill this form out and I will help you as much as I can, if you would prefer to not go to this much trouble there are other people who will help you.

Iboats Boat and Motor Info
1. Year, make and model of boat
2. Length, width and base weight of boat, look for boat decal on back of boat
2a.What is the recommended HP for your boat
3. Number of people and gallons of gas normally on boat
4. What do you use the boat for
5. Is it a Deep Vee and if so how many degrees of deadrise
6. Year, make and model of motor
7. HP and gear ratio of motor IMPORTANT
If you don?t know the ratio, you need to pull the plugs out and put a piece of tape across the prop and the lower unit and then cut it between the prop and the housing and turn the motor until the tape lines up with each other, it is easier if two people do this, so one can watch the prop while the other counts the revolutions of the motor
8. Manufacturer?s recommended Wide Open Throttle (WOT) range
9. Anti-ventilation Plate height above keel of boat if it is an outboard in inches
10. Is it a bass boat or does it have a pad bottom
11. Does it have a hydrafoil, dolefin or trim tabs
12. Make, model, diameter, pitch and whether SS or aluminum prop
13. WOT RPM and speed from your current prop and how much gas and how many people were in the boat for the test data and is the speed by GPS. If you do not have a tach you can buy a Tiny Tach for $ 50
14. Are you at sea level or a higher elevation, give us the elevation in feet
15. Has your motor been tuned up lately and have you checked that the carburetor butterfly is opening all the way, checked compression, and looked at the plugs and checked spark, all of the foregoing could be the reason your prop is not attaining full RPM
16. How long has this prop been on the boat and why, at this time, do you think it is the wrong prop
17. Does the prop show any damage that you can see
18. What problems are you trying to cure or what are you looking for the boat to do that it is not doing the way you think it should or to your expectations
19. If you are trying to attain a better cruising speed and fuel savings or trying to attain a faster speed I will want you to take your boat and run it with 1 or 2 people and give me the RPM and speed readings starting at 3,000 RPM in 500 RPM increments all the way to WOT.

REMEMBER, The numbers I give you will be NO better than the information you give me

The only thing I ask of you is to come back and give me a report of WOT RPM and speed for my database.

H

 

[DGartzos]

Re: 1994 40HP evinrude on 13' inflatable

WOT rpm = 6800 (normal range 5500-6000 requierd 5750)
WOT speed = 30 Knots (34 mph), two persons onboard
gear ratio = Standard 1994 40HP evinrude

 

[DGartzos]

Re: 1994 40HP evinrude on 13' inflatable

1. 1989 Lomac 390 inflatable
2. L:13' W:5.5' Weight: 200Lbs
2a. 40HP
3. 2 people 20 gallons
4. leisure
5. Not a deep Vee
6. 1994 40hp evinrude (with carbs and reeds of a 50HP call it a 45HP)
7. 2.43:1
8. 5500-6000
9. 3/4" above
10. dont understand???
11. trim pads
12. Make: ??? Model: ??? D: 11 3/4 P: 17" Aluminum
13. WOT rpm: 6800 2 persons 10 gallons GPS
14. Sea level
15 Runs like the Milan Opera, tuned like Pavarotie's basso chord all checked recently plugs, sparks, linking, decarbed, timed i tell you like Brahm's violin!!!
16. This prop i have many years and recently found i am running away out of recommended WOT rpms due to wrong setting on tach.
17. Yes most of it has lost paint.
18. a) run into proper rpm range b) to much slipping
19. looking for a balanced all round operation.

 

[hwsiii]

Re: 1994 40HP evinrude on 13' inflatable

D, you need a 19" pitch 4 blade Solas Amita prop and it will bring your RPM down to about 5,700 RPM. It will increase your speed and decrease your prop slip.


H

 

[DGartzos]

Re: 1994 40HP evinrude on 13' inflatable

Hello H,

Thank you for your responce and please bare with me as i am standing mistaken here once more. It is that little arrow on the dial of the tach wich had set opposite way and now i have a new set of readings for you.

1. 1989 Lomac 390 inflatable
2. L:13' W:5.5' Weight: 200Lbs (+ 100Lbs fittings) (+ 200Lbs motor)
2a. 40HP
3. 2 people 20 gallons
4. leisure
5. Not a deep Vee
6. 1994 40hp evinrude (with carbs and reeds of a 50HP call it a 45HP)
7. 2.43:1
8. 5500-6000
9. 3/4" above
10. dont understand???
11. trim pads
12. Make: ??? Model: ??? D: 11 3/4 P: 17" Aluminum
13. WOT rpm: 5400, 33.7 mph GPS, 2 persons 10 gallons
14. Sea level
15. Motor OK!
16. This prop i have many years and recently found i am running away out of recommended WOT rpms due to wrong setting on tach.
17. Yes most of it has lost paint.
18. a) run into proper rpm range b) to much slipping
19. 3000rpm, 14.3mph
3500rpm, 18.3mph
4000rpm, 22.3mph
4500rpm, 26.3mph
5000rpm, 29.9mph
5400rpm, 33.7mph

I am any way going to get a new prop even if i have to get a same one (want to have a spare one onboard). Would i be better of with a 15" original i balieve it is a 12 3/4 in diameter ?

 

[hwsiii]

Re: 1994 40HP evinrude on 13' inflatable

D, I would recommend a Turning Point Hustler 15" pitch prop to stop your prop ventilating so much, as it has a lot more cup and rake than a normal aluminum prop. You actual prop slip I show at only 5%, but I am assuming the speed you gave me was from a speedometer as 5% slip on an aluminum prop is very low. It should bring your RPM right up to the top of your recommended RPM range.
You can buy it right here at Iboats for less than a $100.

Price: $92.98 You Save: $26.52 Compare: $119.50 Discount: 22.3% Off

Propeller Specifications:

SKUrop #H1-1015Hub #11
Manufacturer: Turning Point
Brand: Hustler
Material: Aluminum
Diameter: 10 - 1/8?
Pitch: 15?
Blades: 3
Rotation: Standard (Clockwise)

Usually Ships Within: 1 Business Day


H

 

[DGartzos]

Re: 1994 40HP evinrude on 13' inflatable

H,

I have three means of reading speed and they all have different readings one is an old type dial, works with pressure, the other is NAVMAN which it has GPS speed and a magnetic roller for water speed. The old dial readings are always 10% more than GPS and roller water speed readings are always 10% less than GPS (roller looses grip when planning unless water is absolutely flat).

The measurements i posted are those of the GPS readings. Yesterday was quite windy and little wavy. In order to get each reading I started right at the top of the bay down wind, coming back up wind into the bay readings were lower say about 1+ mph each reading.

I am still confused on my rpm readings.

Just before i adjusted tach to 6pulse for my 1994 40HP evinrude i was getting measurements for you which are as follows:

3000rpm 6.9mph not planing
3500rpm 13.7mph
4000rpm 17.1mph
4500rpm 20.6mph
5000rpm 24.0mph
5500rpm 26.8mph
6000rpm 30.2mph
6400rpm 32.5mph

Going the other way which setting on tach do you think is more likable correct ? !!!

All measurements i get in Knots and have converted to miles using 1 Knot = 1.14 m

Could not find a 10 1/8D 15P blade on iboats just a 12 1/4D 15P.
Blade will have to reach Serifos island Greece, payment by pay pal.

 

[hwsiii]

Re: 1994 40HP evinrude on 13' inflatable

Give me the make and model of your tachometer and I will try and look up the manual to be positive.


H

 

[DGartzos]

Re: 1994 40HP evinrude on 13' inflatable

Tachometer came with motor back in 1994. It does not have a make on it so i assume it is an OMC.



Trying to find documentation for it, i got a hint that my tacho is exactly the same with TELEFLEX and the link below which refers to motor as a 12 pole under the "All other 2-cylinder models" hence setting to 6p

http://www.downloadingfiles.co.uk/t...structionmanuals/99320 rev 10 Tachometer,.pdf

and some days later fall on to the link below which has it under the 10 pole and setting to 5p

http://volkhart.net/Boot/PDF/tacho.pdf

 

[DGartzos]

Re: 1994 40HP evinrude on 13' inflatable

Hi H,

Any news on tacho !!!

 

[hwsiii]

Re: 1994 40HP evinrude on 13' inflatable

From what I found it is a ten pole and not a 12. We started with you saying the RPM were at 6,800, then we went to 5,400 RPM and now we are up to 6,400 RPM which I believe are probably correct because you had it set for 10 pole position, which is 5P. LOL
I have been trying to lock down which is on your motor and I cannot seem to do this. It is either a 12 pole or a 10 pole and I see where you have been trying to find out as well in evinrude section. WE have to have that information right in order to know which set of numbers are right.
I am still looking, but do not have a 100% answer yet.


H

 

[DGartzos]

Re: 1994 40HP evinrude on 13' inflatable

H,

Tested with an oscilloscope and it is a 12 pole generator giving 6 pulses in between each spark, so it is measurements below (speed obtained by GPS in Knots converted to mph - 1 Knot=1.14 mph ):

3000rpm, 14.3mph
3500rpm, 18.3mph
4000rpm, 22.3mph
4500rpm, 26.3mph
5000rpm, 29.9mph
5400rpm, 33.7mph

It looks like i have to go for 15" pitch blade, but diameter 10 1/8 i can not find on iboats.

 

[hwsiii]

Re: 1994 40HP evinrude on 13' inflatable

D, the reason you couldn't find the 10" is because I looked up the wrong one. The Hustler number is Turning Point Hustler #H2-1215 and it is available here at Iboats, just do the search on your motor and go to the 15" pitch and you will see the foregoing number. There is a good chance that you might be able to raise the motor up a notch or two after you install this prop to get a little more speed.


H