Does anyone elses 31 not require any trim or tab? How do you run it?
 

I am just curious how the other 30/31s out there ride. Attached is a picture of my boat running wide open with tabs all the way up and drives all the way down.

Tabs - Do you run with your tabs up up or neutral?
Drives - When I start to get my drives trimmed to around 3 04 4 the boat begins to coem very loose...after 3-5 range it begins to bounce a lot. I am not sure if my boat just doesnt have enough speed (max around 55-60mph) or if my tabs are in the wrong position. Or if the hulls just have a ton of lift and don;t required much trim at all. All I usually use my tabs for it to even out weight from my water tank.

How would you say the lift and ride look from the pictures?

usually use tabs down to 3 to help getting on plane...run neutral once on plane or slightly up from neutral.

Cruiseing (3K rpm) drives are just above full down to loosen up the bow. 4K rpm and up the drives are around 7.

There is that spot where it likes to porpose but is avoidable with less drive trim or a little tab.

So when you say neutral tab ou mean tabs follow he line of the bottom of the hull correct? I usually have them all the way up so maybe that's why ican never trim past 3 or 4 without extreme porpoising

yes level with the bottom of the hull. If you raise it all the way up it just takes that much longer to get the tab to do something. I like keeping it just above neutral so that if I need to make a quick correction the tab only needs to move slightly.

You need to be in the upper rpms if you want to trim way out. Just do some testing and find those sweet spots.

Does your hull have a slight hook of about 1/8" at the rear? It was designed in for stability. Sonic told me it would run very loose and porpoise if removed.

I've never had a loose feeling from my boat and at WOT run the tabs up around 7. However, I've found it's possible to over trim the boat the boat with the drives. It never porpoises, though. It's just loses traction and runs slower.

I also use the tabs down to aid getting on plane or run them neutral or just lower than neutral when cruising about 50 MPH to help keep the boat level over boat wakes and bigger waves.

So what level you would say your drives are at? Just looking for suggestions. Like I sai my tabs have been all the way up and trim around 1-2 feels great but anything past there starts to bounce

I have a 35 and always run tabs level when cruising and drives a couple clicks out (just so you feel it start to free up). WOT tabs are all the way up and drives out to 7 or 8. You can't really go by indicator readings from boat to boat, beacause cabling can be off from boat to boat.

I also switched to Hydromotive's from Bravos, and it made the boat run flatter with less hop. hydros lift the stern....so they dont give the boat as much of a chance to hop.

What props are you running? Sounds like 3 blades. I much prefer bravo 1's. Hydromotives were terrible on my 386. I never ran the tabs on my 31 unless there were swells over 4'.

I got 4 blade bravos 23 pitch

don't think they can be 4 blade 23p they are either 22p or 24p bravos? i have a 02 31 sonic with 496 ho's and run 28p labbed bravo1's

Hell maybe they are 22. I had 23 in my head for some reason. I run about 4800rpm wide open but that has been with no trim what soever... Curious to see what kinf od results I get when I water test.

Ok.... So I water tested today after work and here were my results... I was averaging around 54-57 with tabs all the way up and drives all the way down... Ran it today at WOT with drives around 4 or 5 and acheived 62mph. When I got past 4 on my drives I could feel the rear of my boat lifting out and had no control over steering... You could actually feel the rear of the boat kind of pick up and move around... Not sure what this is called or how it can be controlled.... My previous boat would just begin to throw a rooster tail and fly rpms when trimmed to high...

try running your tabs more level with the drives trimmed out. you wont "chine walk" as much.

you should do this at cruise speed too. tabs level and drives up a couple clicks to free the boat up.

I don't see a response about a hook in the back of the hull. It should be about 1/8" gap over the last couple feet of the boat, if you put a straight-edge on it. If you don't have that hook, the boat will be much more loose.

Are your drives spinning out or in? Outward rotation will give you more stability. How about drive toe? A little toe also provides stability.

I will check for the hook this evening... I felt as if the tab were pretty neutral when I was wot with drives around 5 or so...I felt I should raise the tabs up some to get the rear of the boat down in te water some more

My drives are spinning in

Thats the looseness. It gives an extra 1-2mph, at the cost of stability. You want them to spin out. The 31 is an extremely stable boat. Swap the props and switch the shift cables at the shifters and you will like the boat a lot more.

Good call Plum.

What Go4Broke said, the 31's turn out.

See you tomorrow at the Poker Run... :drink:

Jim take him for a ride in the hot rod. My wife still talks about all the fun we had in that boat. She would love to have it back.

boat looks wet you need more trim also what plum said props out, one of my friends has a 38 with 800hps and those b max drives he should of went konrad ace cause he has blown the maxes a lot. well his boat run b1 props and uses a lot of trim to get it out of the water. the bouncing bow is mostly deep drives and trimmed near the max while cruising. good luck.

U saying I need to be trimmed near the max because of the deep drives?

When I put my 04 31ss on plane, there is an annoying porpising that I throttle through or trim out depending on conditions such as wind, boat load and balance. Changeing props helped a great deal. I replaced the stock Bravo 1 four blade 26 pitch with Hydromotive five blade labbed 25 pitch. What a difference. I feel the new props are better in every respect especially mid-range acceleration.The boat planes easier, stays on plane at lower rpm, and same top end. Best upgrade I've done yet.:party-smiley-004:

5 blade may be the trick. I tried hydromotive 4 blades and they sucked. Buried the bow, I couldn't carry it.

Chris you may be right I have heard the same that hydromotive 4 bladed props and Sonic hulls don't play nice together.

I generally run my 2006 31ss with no trim at all. The exceptions are:

1. When in 25mph and 30mph speed zones I put the trim tabs down which keeps the bow down for visibility.
2. When in minimum wake zone I put the tabs down for the same reason as #1.
3. When in heavy seas( 4ft+) I adjust the trim to keep the boat level.
4. When running high speeds (over 60mph) I trim the drives out for maximum rpm.