Zip setup

Outboard designs up to 14'

Moderator: ttownshaw

Post Reply
sawford11
Posts: 154
Joined: Wed Oct 12, 2011 1:51 pm
Location: Pittsburgh, PA

Zip setup

Post by sawford11 »

So I launched my Zip for the first time over the weekend. Overall, I was pretty happy with the result. One thing that I wanted to ask about was that right around 25mph (and over), the boat started to porpoise. If I backed off the throttle just a bit, it was fine. I have a a couple of things to try, but before I went with the trial and error approach, I fiugred I'd try to gather some input. I successfully built a pretty nice boat, but that doesn't mean I know much about boating!

When I unloaded it from the trailer, it seemed to be a bit heavy in the back. I have a 50hp, 190# outboard and a 60# battery behind the rear seat. I have a 12 gallon tank 'under the hood.' I had 5 gallons of fuel in the tank. I had about 500 pounds of humanity in the front seat.

I am considering a few things:
1. Relocate the battery to the front
2. Fill the tank completely to see what happens
3. change the pin setting on the ouboard**

** I have no idea how these pin settings affect performance and I would like to get some input. I think you can see from the photo below, I can adjust the motor 'in' one more notch, and out a bunch of notches. Any thoughts???
Attachments
IMG_20130522_190548 (1).jpg

Moeregaard
Posts: 366
Joined: Mon Dec 03, 2007 11:31 pm
Location: Thousand Oaks, California

Re: Zip setup

Post by Moeregaard »

Trim your outboard down first. We had a porpoising problem with our Zip, and this fixed it. We're currently running with the outboard trimmed all the way down (last pin setting) and it does not porpoise, regardless of load. We've found that adding passengers to the front seat changes very little, but toss a couple of carbon-based life forms in the aft cockpit and the boat has trouble getting on plane.

-Mark Shipley
A boat is just a wooden box with no right angles.

User avatar
vupilot
Posts: 3650
Joined: Wed Apr 15, 2009 7:36 am
Location: Indy
Contact:

Re: Zip setup

Post by vupilot »

Im not sure if the angle for the second pin position is the same on my Merc as your Johnson but I have tried the first 3 pin positions and I always run on the second one just like your picture. It took trying each to settle on the best one overall. The first hole ran a little more consistently but I gave up some top end speed and got some more spray off the motor. My boat is set up just like yours except with a 40hp.
It always runs great with just two adults of any size onboard. When I put adults in the back with less than half fuel it can start to porpoise but only near top speed, slowing slightly then re-accelerating usually stops it. I've experimented with everyone leaning forward when it starts too and that stops it as well, that's why I advocate for the tank up front if you plan to run a Zip with 4 adults often. Next time I have 4 adults in it I might try 3 across the front seat and the largest person alone in the backseat and see what that does with light fuel. With a lot of fuel my boat will hardly ever bounce the bow no matter how its loaded. Are you positive the bottom aft half of the boat is flat and the transom bottom edge is not rounded off too much? Mine is rounded only about as much as a cocktail stir/straw or like a cord to a cell phone charger.

I would try running again with 3/4 tank of fuel and try that closer pin position too, then try with all different loads of people in the boat and you'll learn what your boat likes and a few minor adjustments should be all you need.

User avatar
Roberta
Posts: 6774
Joined: Tue Jul 31, 2007 5:23 pm
Location: East Troy, Wisconsin

Re: Zip setup

Post by Roberta »

My Zip will porpoise at speeds above 28 if there is some chop. Smooth water is no problem at any speed. I am running my trim in the last hole for best ride results. I am considering Lenco trim tabs, but haven't done that yet. Merc 500 is the power. Aft loading greatly affects hole shot and ride. I have a very light battery near the transom (Odyssey 920) and a mid mounted fuel tank.

It sounds like your boat is behaving very typical of the Zips on the forum. Needs a bit of trim to keep the bow down and does not like heavy aft loads unless you can over trim to counter them.

Roberta
Roberta "Queen of the Boat Builders"
Built Zip "Oliver IV", Super Spartan "Jimmy 70", and Torpedo "The Glen L".

chipper363
Posts: 40
Joined: Mon Sep 21, 2009 2:51 pm

Re: Zip setup

Post by chipper363 »

Smart tabs solved the problem in my ZIP.

User avatar
vupilot
Posts: 3650
Joined: Wed Apr 15, 2009 7:36 am
Location: Indy
Contact:

Re: Zip setup

Post by vupilot »

Ive ridden in one with a hydrofoil mounted to the motor and that made it plane faster and it didn't seem to matter how it was loaded, it rode very well. Their is nothing wrong in the design, you just need to experiment and tune things to how you run your boat.

sawford11
Posts: 154
Joined: Wed Oct 12, 2011 1:51 pm
Location: Pittsburgh, PA

Re: Zip setup

Post by sawford11 »

Thanks for all the great advice everyone! I knew I'd get some good feedback. Since the easiest thing for me to start with is to try a different pin setting, I think I will do that.....along with some more fuel since I'm a bit low ;-)

If that doesn't do it, I'll try to reposition the battery tho not preferred, since my motor cables won't currently reach to the front.

Mike Sea
Posts: 43
Joined: Wed Oct 07, 2009 4:20 pm
Location: North Canton, Ohio

Re: Zip setup

Post by Mike Sea »

I have noticed several post about boat porpoising and in my option most boat porpoising is caused by two much weight in the back of boat and flexing transoms. The Zip's transom as the plans state was designed for a 40 hp motor at that time it would have been a Mark 55, that weighed about 130 lbs. A 50 hp motor that weighs 190 lbs is producing approximately a 40% greater moment on the transom. The increased weight on the transom will cause flexing and this flexing causes the motor movement. Also the flexing will get greater as the speed increases.
I built a boat similar to the Flying Saucer that had a flexing transom with a 110 lb motor. I could get the boat to perform OK by running the motor in the first pin positions but the boat just wasn't running the way it should. We found the flexing problem by applying force to the motor and noticing the transom moved a little. Next step was to reinforce the transom but I was lucky on my boat the rear deck did not go across the back. The boat had a frame about 14 inches from the transom that made an ideal place to mount my transom fix. The fix was
1) A 3/16 alu. plate 14" x 15" with one inch flanges on two side was bolted to the transom.
2) A 1.5" x 2"oak board was bolt to the frame.
3) two 3/4" plywood boards 14" x 12" were attached to the transom plate and frame addition with Alu. angle brackets, that were preloaded in tension.
I put the 110 lb motor on and no porpoising and I could run motor tilt position up to number 4. Since then I have upgraded to a Merc 500 about 160 lbs the porpoising has not returned at any motor tilt position and with speeds up to 43 mph? The only way I can get the boat to porpoise is with the gas tank, battery and two people in the back seat, which is normal with too much weigh in back of boat.

User avatar
Roberta
Posts: 6774
Joined: Tue Jul 31, 2007 5:23 pm
Location: East Troy, Wisconsin

Re: Zip setup

Post by Roberta »

I would agree with the transom flexing with the old design without the motor well installed. A well placed motor well and reinforcement should stiffen the transom. I think the porpoising is mostly exceeding the design speed, too much aft weight, and the inability to get enough bow down trim. All things that can be corrected.

Roberta
Roberta "Queen of the Boat Builders"
Built Zip "Oliver IV", Super Spartan "Jimmy 70", and Torpedo "The Glen L".

Jack Graham
Posts: 2
Joined: Mon May 17, 2010 10:02 am
Location: Dartmouth Nova Scotia Canada jackgraham@ns.sympatico.ca

Re: Zip setup

Post by Jack Graham »

Porpoising can also be caused by having the cavatation plate on the motor to low in the water. I was always under the impression that the cavitation plate on the motor should be in line with the botom of the boat. I just purchased a new 30 hp Honda for the zip I am building and Honda states in their manual that it should be one inch be low the bottom of the boat. I have to raise the transom before I mount the engine so I am leaning towards having the cavatation plate in line with the bottom.

sawford11
Posts: 154
Joined: Wed Oct 12, 2011 1:51 pm
Location: Pittsburgh, PA

Re: Zip setup

Post by sawford11 »

I had the boat in the water again this past weekend. I took out the 60lb+ deep cell and replaced it with a 10-15lb battery instead. I kept the battery just behind the rear seat where it was positioned before. I also filled the tank (12 gallons) and moved the anchor (15 lbs?) to a storage area under the hood. Lastly, I trimmed the motor to the first pin. With all of that in place, the porpoising went away (mostly) at speeds below 30 mph. The lake was very choppy with high winds. In the parts of the lake with the most chop the porpoising was more exaggerated....although I am not sure it was porposing as much as violent smashing against the waves!

With the addiotional reinforcement that I did with the motorwell and transom, and some extra kickers between the transome and battens/seat frames, I dont think my transom was flexing. It's possible, but I don't think so. It seems the respositioning of weight really took care of things pretty well.

User avatar
jeffh
Posts: 1521
Joined: Thu Feb 25, 2010 10:34 am
Location: ATL Burbs and Lake Chatuge, GA

Re: Zip setup

Post by jeffh »

I installed a hydrofoil over the weekend and it improved my ride quite a bit.
viewtopic.php?f=2&t=24595
2011 MALAHINI - KICKED IN THE HEAD
Image
I wake up with a 16ft woody every morning :)
Video: http://www.youtube.com/watch?v=534DBtp1Cnc
Website: https://sites.google.com/site/2011malahini/

Post Reply

Return to “Small outboards”