raising motor for more speed

[RichW]

Attached is a pic of my yammie 70 on my Alweld. Yard stick is taped to the bottom of boat and motor is trimmed about to where I get max speed without porpoising (gps 33 @ 6100 rpm). Prop is a 13p powertech Question; I'm already in the 3rd hole, so I can raise one more hole. Good idea or not Thanks

[Great Scott]

Delete double post

[Great Scott]

It could work, but then again, you
may loose all of your water pressure.
I would only do this if you have a WP
gauge.

Looks like you are maxed out on RPMs
You need a heavier pitched prop. If going higher
works, you will turn a few more Rs. LDS

[Panama]

Attached is a pic of my yammie 70 on my Alweld. Yard stick is taped to the bottom of boat and motor is trimmed about to where I get max speed without porpoising (gps 33 @ 6100 rpm). Prop is a 13p powertech Question; I'm already in the 3rd hole, so I can raise one more hole. Good idea or not Thanks

What size Alweld is it??? I don't see a signature or anything about the boat, but maybe my iPad doesn't see it. Sometimes that happens.

My opinion is that there is no way that I would take it past the third hole without a water pressure gage. No way, no how. If it is a 17 ft boat I would expect a better speed.

[gatorglenn]

What size boat is this. If you have to run the motor tucked that for under so it won't porpoise. I'd say your to high now. Your bow would be plowing. To really get more speed the motor needs to have the cal plate level with the yard stick and slightly downward in the other direction from this picture. I ask the size because you typically don't see a 13p prop on a 70hp unless it like a 18' boat.

[RichW]

boat is just shy of 18 ft, I've got a water press gauge and t's got good pressure in the 3rd hole. It's a stick steer and sure thought that my yammie would push it faster than 33 Here's a pic

[Nova Kaw 650]

boat is just shy of 18 ft, I've got a water press gauge and t's got good pressure in the 3rd hole. It's a stick steer and sure thought that my yammie would push it faster than 33 Here's a pic

It probably will. 13" probably isn't enough pitch.

[Great Scott]

I dont have a clue what your boat would run with a wheel or tiller handle,
but you can count on a little less, because your motor is having to try
and lift your body weight, w/you sitting up front. I would suggest a higher
pitch number or even dropping it a hole. Your seating position makes a
difference in setup. LDS

[Karma Got Me]

Yep I would drop it a hole and see what happens. I agree it looks like the nose is plowing and the porpoise is from the prop losing bite.

[krr6581]

Correct me if I'm wrong, with a stick steer the operator sit forward of center of the boat. This is why the front of the boat plows and is also probaby the reason your only doing 33 mph. My Dad had an old KingFisher fiberglass boat with stick steer. It was rated for 40hp motor and we had a 40 E'rude on it. Due to it's weight that old boat probably could have handled a 60 to 70 horse motor with ease. Getting back to my point, that boat always ran fairly flat and plowed just like your boat because there was just no way to get enough lift to get a lot of speed out of the boat. When I finally got the boat from my Dad it plowed like a barge but man did I catch a lot of fish out of that boat.

Because of your boat being stick steer you are probably getting the best your going to get at 33mph and will have to live with a little plowing of the front because your body weight forward of the boats center of gravity holds the front of your boat down. Now you put a 90hp jet drive on that boat and you will have one hell of a shallow waterboat able to get in those places some of us wish we could get into.

[Karma Got Me]

I've seen plenty of stick steer boats running with the nose up in the air. These old guys around here really know how to set them up to run.

[gatorglenn]

Well with that stick steer. Do your best to make it run flat. At this point I would leave the motor where it is and go to a 14or15p prop.

[krr6581]

A 15P would probably give him more lift but his RPM's would suffer and maybe his speed too.

[GeauxTide]

You have no lifting surface and front seat driving limits your performance to where it is.

[RichW]

should I raise and or try a Lazer II 14P?

[Karma Got Me]

I would look into getting your existing prop tweaked to provide more bow lift.

[gatorglenn]

If this was a 15.5 to a 16.5 length boat. I would try to bow lift. But at almost 18' with a 70hp the 14p Lazer (stock) prop would be great no cupping added. Leave motor where it is. To keep rpms up.

[Tjmoberly]

Sure you’ve fixed this by now but I just purchased the exact same boat and have a 13 1/2 x 15k prop on my 70hp. RPMs are 6300 and top speed with two adults a 3yr and a 3month is 36mph.