porpusing (bow bouncing up and down)

[Beck]

Finally got to take my Tims 16x54 custom flat out for a test run. Powered by a 1989 Johnson 48 spl mounted to a CMC Ptt. Setup is (2)batteries rear compartment by motor. In front of that is a storage seat area, misc. junk little bit of weight. Then, in the boat (1) 60 quart ice chest and a six gallon gas tank. Two guys and fishing gear. <br /><br />I posted a question a while back about the height of the anti-ventilation plate and it was said to start at about 1 1/2 to 2 inches. Instructions say 1-3" Well I thought I was 1 3/4" but it appears I measured the plate right above it and in fact I was 1/2" below the bottom. <br /><br />Test run front of boat kept bouncing when I trimmed down to stop bouncing notice water splashing by transom (too much motor in water) finally had to put ice chest and gas tank in front of boat. This helped alot.<br /><br />Just wondering, should a boat have a bit of weight in the front of the boat? How balanced should a boat be? I know port to starboard should be balanced.<br /><br />Today I raised the motor to the higest point which puts the a/v plate 2" above the bottom of the boat.<br /><br />I plan to extend the front deck and this will give me a large storage area. I could put the trolling battery in it and also 1 or 2 6 gallon gas tanks. Just wondering if it will be too much weight.<br /><br />Any opinions would be appreciated.<br /><br />Beck

 

[QC]

Re: porpusing (bow bouncing up and down)

Unless there is something wrong with the hull, porpoising is all about weight distribution fore and aft. It can be corrected with trim tabs if you would prefer to keep the weight in the stern and/or want better planing times and lower planing speeds.

 

[Beck]

Re: porpusing (bow bouncing up and down)

Quietcat,<br /><br />Thanks for the reply and I don't really need to keep the weight in the rear. In fact with both batteries in the rear compartment I cannot access the small buckets that I keep there also. As this was a maiden voyage so to speak. I just swapped my engine and lots of other stuff from my 14' riveted to this custom welded. <br /><br />How do deep cycle batteries or any other batteries fair out in the front of boats with the pounding from waves, etc.? I know the gas tanks will be ok, it's just at the end of a trip I figure the gas will be gone and still needing the weight up front, a battery would keep some weight there.<br /><br />I may even mount my ice chest up front against the extended front platform I plan to build. Hopefully when your getting lighter from the gas tanks you would be offsetting the weight with fish! Wishfull thinking?<br /><br />Beck

 

[rg33]

Re: porpusing (bow bouncing up and down)

Originally posted by Beck:<br /> <br /><br />Test run front of boat kept bouncing when I trimmed down to stop bouncing notice water splashing by transom (too much motor in water) finally had to put ice chest and gas tank in front of boat. This helped alot.<br /><br />Beck

Try this: Motor should be trimmed down when first pulling off, then trimmed up to control the bouncing.

 

[stevens]

Re: porpusing (bow bouncing up and down)

You could check out the booklet on boat balance over at nauticusinc.com , or wait for NautiJohn to answer. He should be here any minute now....

 

[AntsGrady]

Re: porpusing (bow bouncing up and down)

Trim the motor, buy trim tabs, more weight up front to balance, or a hydrofoil. These are you options. Smart Tabs would probably be the best application for your size boat but a hydrofoil may to the trick also. Good luck.

 

[Jdeagro]

Re: porpusing (bow bouncing up and down)

Beck;<br /><br />Obviously small boats are very prone balance and handling issues from minor changes in positioning of equipment, motor HP and weight, etc.<br /><br />You could play the balance game from now to eternity and never win unless you keep every thing the same all of the time. including people. Not practical.<br /><br />Try to maintain some sort of balance within reason, then put trim tabs on the boat to compensate for all of the other changes and issues. For your size boat Smart Tabs would be ideal, and not break the bank.<br /><br />The porpoising is common, and simply means that the weight balance is more to the stern than it should be, but that may not be avaidable.