controlling porpoising
 

Out this weekend and on Lake Ossipee and had some time to mess around with trim at speeds and tab position. I was noticing while cruising around 45ish I would get a lot of porpoise action ( up and down ). When this would happen I would try tabs and or trim but didnt really seem to fix the problem unless I'd hammer it and around 60 it would go away or if I backed off. Its a 216 convincor 454 B/1 23 p mirage. Didnt know if anyone could shed some light on it or give me a tip to try to right the issue. 45 is the speed I like to cruise at or around and it can get frustrating

Any help or thoughts would be appreciated

Thanks guys

Is the porpoising from the tabs digging to deep or not enough ? The tough part is I dont have indicators so it is not easy to know where exactly I am at with them

it could be because the drive is to deep in the water at that speed !
Also an other prop can resolve this issue and yes if u dig the tabs down a tat it can also help.

The boat is pretty much stock never messed with the drive. What would cause the drive to be too deep??


Also what would be something to look for in a prop to possible alleviate some of this problem and maybe boost overall performance at the same time?


Thanks

my boat will do the same thing around the 35-40 mph mark if i trim the drive up to much. i tap the drive down a touch at a time till it goes away.
you go in the ocean at all, im up that way all the time with my boat. we go to winggi all the time. spent all weekend there.
not sure your location but if you wanted to meet up some time next week after work my boat will be out of the water and i can let you try out my labbed 4 blade 24p

oh yea, im right in peabody

Convincer216,

I see you are on Ossipee as am I. I have an 87 25 GTX white with red white and blue style graphics. My boat acts the same way unless I drop the tabs way down. Speed when it occurs changes depending on load and fuel but usually around 35-40. It would be great to see another Checkmate out there sometime! I've only seen a few, you may have been one of the ones I saw last year. I'm usually at Long Sands or the sand bar stop by and say hello if you recognize the boat.

Hey Noyzee
I actually grew up in Peabody We have a couple mutual friends I think (The Perry Sisters) Scott and John

I go to the beach all the time not yet this summer though I used to have a P O S scarab last year and decided to buy a real boat this year

Id love to try that prop out if u wouldn't mind

Wpddep I unfortunatlly dont have a place up there my buddy does on Levitt bay

I get to go up there a few times a year and love it

Were you at the sand bar this weekend because I didnt see hardly any cool boats all weekend That lake seems like a pontoon boat heaven


I did see what I think was a mid 80's Exciter up there that was tan on rootbeer brown nice boat u familiar with that boat

The porpoising comes from the boat trying to get up and run on top of the water and then falls back off. At the speed you are running is the breaking point of when the boat gets on top of the water or comes back down. Checkmate has a good hull design and their boats have no problem getting on top of the water and running with minimum power. Unlike a lot of boats that tend to push the water Checkmates hulls like being on top.

This is good because a fast boat is on top of the water not pushing the water. The bad is you get porpoising at mid speeds most all Checkmate Deep Vs do this. Seat time and trim down is the only cure Stock bravo 1 4 blade props seem to work best I feel in controlling the problem.

And their is nothing wrong with the drive to deep

Well put! :ernaehrung004:

So basically its just a trial and error kind of a situation


Would switching props to say a 4 blade help this problem or only cause it at different speeds?

Like I said that is the speed that is really comfortable to cruise at so it would be worth a swap if it would help





At least its a reason to go out and burn fuel or at least thats what I will tell the wifey

curious as to how I can post pics .....Ive been told I cant post because I am only registered but I have seen a bunch of guys on here that are just registered who have pics posted


Would love to be able to show of my baby haha

i just saw this post. lol
yea, scott and john, yup. scott is coming out tomorrow as well.
should be fun.
was it the blue one? the scab?

I have wanting to try a labbed hydro prop...I have been told that a labbed 25 pitch cut down to 15.25 inch is the way to go...It causes the stern to lift and stop the porposieing alot...which with a bravo 1 prop its a bow lifting prop and causes the porpoising more....

Hi everyone
Reading your issues with porpoising, this is a hull bottom issue, more than likely you have a hook or bump in the bottom of your hull that causes this type of reaction while at crusing speeds, it very difficult to correct the problem with trim tabs and if you do correct the problem the boat will not be running very efficiently, you are causing major drag to keep the nose down.

Check the bottom of your boat, with the boat on the trailer take a stright edge and place it in line with the keel and move the stright edge out board, and see if you see light or the stright edge rockers.

JR

i have checked mine and its fine. it does it at one cirtain speed with the drive in one certian spot. i usually dont have to tab. either bump it 100 rpm or touch the trim down. i was more under the impresion that it prop grab/slip

Yup, WildWilly is right. Pulling the drive in a tich is the easiest. When you are in that mid RPM range with any positive trim they can start porposing. Pull the drive in a bit or give it more go juice.

i checked my hull. i had a few very minor imperfections in it mainly slight discoloration, could be just from the iron and cleaner used in the first 5 years the boat was on a lake taken care of by someone else. but i have layed a 4 foot straight edge out all over mine and cant find anything. i think some of it is the slight roundness to the V or maybe the small notch in the stern or a mix of both, but atleast on my boat its not a hook.
also, just about every 24-26 foot boat i have been in will have this issue at the perfect spot

OK
I was understanding that there were serious issues with porposing even when trimming the drive if its just a bump with the trim and its corrected, most all boats have that sweet spot for porpoising, it just a matter of knowing what to do with the boat to correct the problem, also most boats are designed for specific speed ranges and the type of boating you may be doing.

Many manufactures dont test their products through all the speed ranges to make sure the boat performs well through all the ranges, some boats are designed to go fast and handle rough water and others are designed for more family use for water sports ect and then there are those that try to hit several different markets, go fast, family, and water sports, and this is tough to accomplish because of all the different loads and center of gravity issues when developing hull forms.

Normally theres a forced compromise some where with in the design of the hull form to meet the customers needs and many times the customer is sold the wrong boat to fit their needs, but they want the cool looking boat, that the challenge to the manufacture and the design team, this is also where sometimes the manufacture is labled as a POS because the boat was not really designed for the proper market.

Just 25 years of my product development insight.
JR

talking with a friend with a 26 Sonic (and they porpious (sp) ) also he has problems getting on plane in following speeds. Well he was talking to a very well know Velocity guy her on OSO Bob Powell. He told my Sonic buddy to run the drive neutral and adjust the attidtude of the boat wiht tabs. He tried it and the Sonic handled much better. Not the fastest but the ride was comfortable in those mid ranges and following seas. I have not tried it yet but I'm going to. Bob is a pretty smart guy and knows how to drive a boat so I tust his recommendations.

Hope i am not being misunderstood ( which happens to me)
I totally agree you can trim and tab a boat to react as you need it to, there are other alteratives if the boat is very uncomfortable and the user loves the boat, but hates this porpoising problem in what ever range cruising speed it shows up at. some slight bottom modifications can make a huge differance in desired performance.

i have worked on several boat manufactures bottoms and their are alot of claims of how the boat will perform then when the customer starts using the boat, it just dont quit meet the expectation, I have altered alot of boats to help customers get the performance they are looking for, and having the customer test the alteration to make sure the boat performance fits their needs.
So just something to think about.
JR

Its all good!

it seems like boats with rocker or hook do this, which is a lot. 3# cig/baja/saber all do that two. anyone know how to contact the guy with the 30footer #6 drive, I need to ask him about his CGon the 30, if he changed anything. in a week or two I'll have a porpoising vid on here:eek: you'll LOL, I have a big blower motor plus a konrad ace hanging off the back of the saber. long story short it would porpoise then on the 5th or 6th it would start to leap out of the water.:eek:.I heard blue printing the hull will stop it. heard the hook or rocker was added in most boats to help get on plane and pull easier out of the mold. noysee has a nice one for sale 26, wish he would keep it. Artie