Bouncing Boat

[brentcausey]

We were at the lake tubing yesterday and the boat kept wanting to bounce and I kept having to slow down to prevent it from happening. It's a 18 foot sun bird runabout. We had 8 people total in the boat. Does this mean there was possibly too much weight up front? I was having to cruise around 20-30 mph. If I went over 30 we were constantly bouncing and it started to get uncomftrable. It wasn't a fast bounce it was a slow up and then down up and then down. Thanks!

 

[tashasdaddy]

Re: Bouncing Boat

#1 you are probably rated at 6 people, 1100 lbs max wt. read the plate on the boat. the bouncing is called porposing. usually taken care of by trimming the engine. the max weight rating on the plate in the boat, if an outboard, includes the engine, fuel, gear, beer, and people. if an I/O don't include the engine. Yes you were definately overloaded. my 23' Deck boat is only rated for 11.

 

[Scout Sport Fish]

Re: Bouncing Boat

Yep, classic case of over weight/people on board. My boat is 18 and is only rated to 6 people. (1100 lbs I believe)

 

[delsol]

Re: Bouncing Boat

if you started sinking fast does all 8 know what 2 do??? if not you better tell them before hand .all you pass. even 3-5...like a fire drill . have a plan i used to go off wpb fla. alot with a few people and storms would come in i always had a plan. a couple of times i almost beached the boat. but was able to get the boat in the inlet. guys like me can pilot a 14' boat with exp. better then a guy with a 25' boat with no experence. they will sink before i do as lack of experence.not tellin lies . just the way it is.
bob

 

[tashasdaddy]

Re: Bouncing Boat

Delsol, i agree with you 100%. the guy doesn't even know the capacity of his boat.

 

[delsol]

Re: Bouncing Boat

also any plam is better then no plan
bob

 

[brentcausey]

Re: Bouncing Boat

Delsol, i agree with you 100%. the guy doesn't even know the capacity of his boat.

Did I say that I didn't know the capacity of my boat? The capacity is 8 people or 1400 pounds. I've been driving boats for years, just never had one do what this one was doing. Thanks anyways......

 

[brentcausey]

Re: Bouncing Boat

I'd like to meet someone who doesn't see the bright yellow sticker with the rating on it.

 

[Boatist]

Re: Bouncing Boat

The normal solution to porposing while on plane is to trim the motor in or down until it just stops. You want the boat as balanced as you can so more weight from the middle back than in the front.

 

[Scaaty]

Re: Bouncing Boat

Did I say that I didn't know the capacity of my boat? The capacity is 8 people or 1400 pounds. I've been driving boats for years, just never had one do what this one was doing. Thanks anyways......

Jezzz..
Ever think to add that tuber, which creates WAY TOO MUCH DRAG??
Ya got 8 people in a 18 foot boat, (care less on the plate weight..your OVER) dragging a tuber, and ya just tear up the shoreline and everybodies dock with the wake.
THAT YOU ARE RESPONSIBLE FOR.
Others docked boats slamming into docks with the massive wake ya leave)...sorry. You need to add it ALL up, then ..(ahh the hell with it,..I simply don't like irresposible people that could care less of the damage left behind from thier wake).
If ya get my drift..I hate wakeboard boats and off plane tubers..and I'm entitled to my opinion as I have boats beat to death at my slip from careless people leaving massive wakes..

 

[LubeDude]

Re: Bouncing Boat

Wait just a minute here, you guy`s are assuming way too much about this guy, I would be surprissed that you didn`t run him off. We don`t know where he is tubing or anything else. What are boats for other than fishing out of if not spending time with the family. Ya, I don`t like the waves of those boats either, but when I take the kids out to tube, I make waves too. That`s the rage right now. His family, his boat, his responsability.

I say we owe him an appology!

 

[Aquaman]

Re: Bouncing Boat

I say we owe him an appology!

If I were him I'd neither read nor accept it.

 

[QC]

Re: Bouncing Boat

Well I am sorry brent . . . and I welcome you, your boat and your tuber to iboats. Also our good friends here (they are BTW, but seem to have either dipped into the sauce or have other issues), have not given you correct info either. Porpoising is caused by a weight imbalance, however, it is not solved by putting so much here and so much there via some prescription, it is handled by seeing what stops the porpoising . . . And usually that means shift some weight forward. Also, in my experience passengers move around, so if they are your weight difference you have two choices: constantly tell them where to sit, or install some type of trim tabs. My personal preference is helm adjustable like Bennett's, but Smart Tabs are a wonderful product, they are easier to install and they cost less . .

Rock on dude and again, Welcome!!

Will anyone here who has never ran their boat at capacity please KMA

 

[brentcausey]

Re: Bouncing Boat

Thanks Guys. The lake that I'm running on has no docks or docked boats remotely near the "main lake" that we tube and ski on. There are plenty of small coves and other parts of the lake that have docks, including ours. If an 18 foot boat wasn't supposed to hold 8 people or 1400 pounds then why does the Cost Guard stick the yellow sticker on it? I love how people jump to conclusions. Just because it says cadet next to my name doesn't mean I'm new to boating. This is my 3rd 18 foot runabout and I've never had one "bounce" the way this one did. Thanks for those of you who answered.

 

[studlymandingo]

Re: Bouncing Boat

What course of action have you tried to reduce your porpoising issue?

It's always good to post your results here as others who are searching for related issues can see what you have done to correct your problem.​

 

[Jdeagro]

Re: Bouncing Boat

Brent;

I am sure that all of the guys who jumped on you about too many people in the boat have been "sensitized" to the issue by some bad experience, however a few questions up front would have cleared you of these "crimes".

The boat hull dictates the performance of the boat in every respect so comparing the boat to others may or may not give you answers.

We make Smart Tabs (this is not a pitch for our product) and over the past seven or more years we have come across some strange issues. most often porpoising is caused by too much stern weight, making the bow "light" and prone to bouncing. The common cure is to trim the motor down more so that the stern is lifted and extra pressure is placed on the bow to hold it down. Although I have a problem with this it does help.

WE have noticed that in some cases when a customer uses the wrong set of Smart Tabs with too much actuator pressure, the bow is forced down in the water so much that the porpoising is induced or even exaggerated. Too much bow weight (too many people up front) would tend to give the same results.

Here is what happens: The bow is pushed so far in the water that the water simply squeezes it back out as soon as the boat attitude changes a bit. Remember air is thinner than water so the bow wants to come up, but you have bow pressure pushing it back in. So bow goes in , water pushes back out, and the cycle repeats. Boat balance on a small craft is easily changed for the good and bad by just a few people or load changes. If you run with near full loads then you will need to be especially aware of the boat balance.

Remember that your boat weighs in at about 2800 Lb. without people. adding 1400 Lb. is adding 50% of the load. Now the total is 4200 Lb. and 1/3 of that weight is mobile.