Evinrude 70 prop for speed

[Flex]

Flex
the prop on craigs is a slightly different number to what you posted, you got the 5 & 9 mixed up mate,
I looked at the pic its actually 389510 and yes its a 13x19 yes it fits your engine and yes it is a genuine omc sst prop. its the new one than what I have.
these also have a touch more cup to them than the older ones.
that will give you over the 40mph mark. probably more like 42 to 43, these have good low slip numbers as they bite well.
mine gives a slip of just 3.54 % and shows 43.02 mph and my boat is a pig when it comes to hydrodynamics. ha ha .

Awesome! thanks so much for your input! I will see if I can talk him down a bit and pick it up!

[Flex]

So water was very rough today, got to run in some coves. With the 13-17 SS speed went up to 37. I am positive I can turn a 19 now, and probably 21. Still launched up on plane effortless.

[phillnjack]

glad to see you had a good day out giving it a go.
37 is bang on the money for about 5800 rpm.
do you have a tacho / rpm counter in the boat ? this would help you see if engine is giving its best performance, and you can then
prop it from there to make sure its not lugging at all.
its a shame we are not close as I have a few props you could try out and then see what you need to give what you ideally want..
Have you got power trim on the motor ?

[Flex]

The tach will be here this weekend hopefully and I'll set up for next time out. Rpms sounded right at WOT.

Manual jack plate and manual trim. Have it trimmed as high as I can without porpoising. I think I can move the jack plate up a bit, but need to have someone else with me so I can go back and look at the motor while running on plane.

[phillnjack]

I am going to cheat with looking at the cav plate while running, I have my little borescope camera rigged up on the top of
the transom looking down so I can see it on the phone.
they are dirt cheap , water proof and come in so handy on the motors.
but a friend will do at a push, once you know what is happening you can always dump him on the bank or over the side ha ha .
idealy with the 17 prop you are using you want the cav plate about 1/2 inch above the water, any higher and it will slip like mad, they dont like
running high like some props.
if it was a raker you could go up another 2 inches easily and still have plenty of grip, they are designed very different.

But the 37 is not bad going and will probably only drop 1mph with 2 of you on the boat and still pull away good.

[Flex]

Update, guy is flaking that I was supposed to get the 19pitch stainless from. So I am still running the 17, and have not had a chance to hook up the new Tach yet.

But, I did have another guy with me this weekend when we went out so I was able to go check out the motor when we were at full speed. The Cav Plate is just touching the water at Full speed. So I will be raising the Jack plate about an 1 inch as well as installing the tach before next time out. I think that should help me gain a bit more speed and RPMs, but more importantly, allow me to run even shallower. While fishing this weekend we idled in about 1 ft of water with no issues, and push poled through 6-8" No issues. There was debris around and in the water from recent rain, so did not want to push the speed through the shallows yet.

[phillnjack]

glad to hear your enjoying it, just pay the man the asking price for that 19, its a cheap prop.

[Flex]

Been crazy windy here. So haven't been on the water. But did put the tach on and raise jack plate about an inch today. Hopefully can run it one afternoon this week.

[phillnjack]

The weather over here is not good for boats at the moment neither.
cold, wet and very windy.
we had storms down the south coast last week and even snow last week, real crazy weather,
2 weeks ago we had brilliant sunshine with 28 deg Celsius !!!! hotter than Athens, now we are suffering for it ha ha .
no good for those of us who want to play in our boats...

[Flex]

Pretty nice weather today. Was windy but we ran down the river away from the lake.
So jack plate is about perfect where I moved it up too. Boat hops on plane even quicker, and rides with the bow quite a bit higher. I definitely need more pitch. This was the first trip with the Tach. At 30 I'm running 4800rpm. 35 is 5800, and it would scoot up to 37 for a second. Never even gave it 100% and we had two adults, and two little ones + gear.

[phillnjack]

by those speeds you must be running the 17 pitch. or a modified 15
go up another inch and try the 19, you can easy drop down a touch, but I would say 1 more inch first.
youl should top out at about 6100 to 6300 with a 19 with just you in the boat, that will be around 44.
and with just you a 21 will get you moving in the high 40's.
youl need to vent the 21 to get a realy good holeshot, 12 mm vents will be ideal.

[Flex]

by those speeds you must be running the 17 pitch. or a modified 15
go up another inch and try the 19, you can easy drop down a touch, but I would say 1 more inch first.
youl should top out at about 6100 to 6300 with a 19 with just you in the boat, that will be around 44.
and with just you a 21 will get you moving in the high 40's.
youl need to vent the 21 to get a realy good holeshot, 12 mm vents will be ideal.

Yes, still running 17 pitch stainless. Hoping to get a 19 or 21. I think 21 vented would be perfect.

[Flex]

Finally picked up an OMC Stainless 13x19 prop!!! Hopefully will get to run it this weekend! I'm excited. Will run it and maybe tweak jack plate a bit more if possible. I am just trying to be a little cautious because I don't have a water pressure gauge.

[Flex]

Well, finally got it on the water to run the 19 pitch today.
Results were less than expected for sure.

No top speed gain. Ran 37 at 5300. Also bow wasn't lifted as high. Acceleration was still pretty great. Cruising is a little nicer was going 34 at 48-4900rpm.

I was expecting more speed out of it. Would raising Jack plate another 1/2" or so make that much difference?

Prop blades are almost perfect. Prop housing has some corrosion.

Not sure what's up with my results. To over red so bad with the 17 omc stainless, and not turn a 19 omc any faster..

Open to comments, ideas, criticism, etc. Thanks guys.

[Flex]