Flotation boxes on fishing boat filled with water!

JPTL

Seaman
Joined
Sep 20, 2003
Messages
51
I have a 16 foot Lowe aluminum fishing boat, and there are two large boxes up against the transom that got filled with water over the years. The water got in through silver dollar size holes on the top of each box. It appears that these holes had plugs at one time. The boxes are riveted shot, so I assume that they are simply for flotation, and they appear to be foam filled.
Does anyone know what these are called, and how I can get the water out of these boxes?
 

roffey

Commander
Joined
Nov 22, 2012
Messages
2,187
I can't see how flotation would be hollow let alone have a hole with out with out a plug. Wondering if it is some sort of storage or holding tank/box maybe? Pictures speak a thousand words.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,036
Are the holes on the bottom of the boxes? That would be consistent with floatation. The foam would normallyt not absorb water, and the holes on the bottom would let any condensation drain. Is that what you have?
 

ricohman

Lieutenant Commander
Joined
Jul 30, 2011
Messages
1,631
I've owned one of these boats and these compartments are filled with foam through holes in the top.
But there are holes in the bottom for drainage, they are not sealed. The only way you could fill these to the top would be to slowly freeze them and then leave it exposed to the winter rain or snow.
But I can't imagine how long this would take.
Was the boat submerged at one point?
 

Watermann

Starmada Splash of the Year 2014
Joined
Jan 12, 2013
Messages
13,747
I would have to go with the left out to the elements for years without being covered. Remove the tops, dig out the foam and replace it with some rigid foam board. Then rivet the tops back on and seal the hole in the top.
 
Joined
Mar 1, 2005
Messages
923
Is it possible that somebody intentionally did this in order to create a wakeboarding boat? Of course, it's a terribly unsafe idea but still theoretically possible.

Pictures would be helpful. Floatation can get water logged and it's best to pull it out and replace. The boxes should be sealed if possible.
 
Last edited:

JPTL

Seaman
Joined
Sep 20, 2003
Messages
51
First of all, thanks for taking the time to reply to my thread. I appreciate all of your suggestions/thoughts.
I've owned one of these boats and these compartments are filled with foam through holes in the top.
But there are holes in the bottom for drainage, they are not sealed. The only way you could fill these to the top would be to slowly freeze them and then leave it exposed to the winter rain or snow.
But I can't imagine how long this would take.
Was the boat submerged at one point?
Ricohman is correct here. These are factory enclosures that are filled with foam (likely through the holes as ricohman suggests) and the 'boxes' are riveted to the hull and floor, so they can't be opened without drilling the rivets.
To address the speculation about how long it would take for large foam blocks to completely absorb water, I can venture a guess: 5-7 years of being uncovered, with the holes unplugged, and the stern of the boat filled with water and debris over the winter. Aside from drilling the rivets and removing the foam blocks like Watermann correctly suggests, I guess 5-7 years to let the water seep out the bottom with the holes plugged is the easier, less effective approach :chargrined:
Fortunately, the boat, engine, trolling motor and trailer were all given to my son (knowing that I'd get it back to snuff). The neglected Johnson 30 now runs like new, and the boat looks great, thanks to countless hours of power washing with bleach detergent. The waterlogged flotation boxes are the only issue. An issue that we can live with, I guess.

..and the boat will now be properly covered for the rest of its life.
 
Last edited:

mjf55

Chief Petty Officer
Joined
Jun 17, 2014
Messages
462
JPTL, I would not live with the waterlogged flotation boxes. They are put there for a reason, in case of a really bad problem, and you would not want to compound the situation if that occurred.
In addition, the added weight of the water in the foam will cost you speed, gas and flotation profile ( i.e. stern lower than it should be. )
You have recovered the boat this far, go the extra mile and do it right.
Just my opinion, but I know I would be kicking myself if I did not.
 
Joined
Jul 16, 2016
Messages
23
JPTL: Have to add my two bits worth after I agree with the above advice. Those boxes filled with foam are required by federal regs regarding level flotation. At one time only one point of the boat had to remain above the surface. Now, when swamped, the boat must remain level so the occupants can get in and be protected from the weather, sharks etc. You will see a lot of current models of older designs of Jons that now have this extra flotation to hold up the stern when swamped with heavier engines. It also lets the manufacturer rate for a heavier engine with higher hp rating for the boat. Do whatever it takes to replace the foam, but beware that some of the pour in place foams can eventually soak up water. The federal regs specify how long the foam flotation has to resist soaking up a small % of water, but a few years is not covered by the regs. If you use board foam, do not use the expanded bead type. I just finished a 30 day test on samples of extruded and bead foam, and the bead foam had water in the tiny fissures between the expanded beads. The extruded foam was dry. If salt water gets in and under the foam it can create crevice corrosion as without exposure to some oxygen, the alu oxide coating breaks down and cannot be replaced.
 

fhhuber

Lieutenant
Joined
Jun 19, 2014
Messages
1,365
Not only are you missing out on the potentially lifesaving flotation, the boat is hauling around a lot of useless weight, effectively reducing its useful capacity. You have to count that weight vs the rated load.

Maybe cut inspection ports and dig the foam out... maybe drill out the rivets. One will be easier. (probably drilling the rivets)
Cutting panels of foam and inserting will be cheaper than pour in. That means going in by drilling rivets.
 

JPTL

Seaman
Joined
Sep 20, 2003
Messages
51
Wow. When I asked the general question I was expecting mostly speculation and maybe some experienced opinions. In return I got the latter - answers that were clearly thought out from experienced boaters. I truly appreciate the time that each of you took to reply.
But I didn't think for a moment that I'd actually get an answer from an expert on federal requirements regarding flotation! Capt'n Caution, I really appreciate the expert answer. I can now share your wisdom with my son, so that he (and I) can start to prepare to replace the foam blocks. I will also turn this situation into a learning experience that will only make him think about safety on the water - the importance of flotation and life saving devices, which admittedly I was downplaying myself. Come to think about it, you have me thinking as well....
It's not stupid that Lowe permanently riveted these boxes together instead of screwed together, like I had suggested to my son...it's probably a federal requirement. What would the majority of folks do with these boxes if they could be easily opened and the foam removed? Put some hinges on them and turn them into two nice tackle and gear boxes, actually adding weight to the stern! These boxes are designed to offset the weight of the engine and maintain buoyancy in the stern when the vessel is swamped (possibly from losing or forgetting the drain plug??) They serve no purpose when above water...or do they?
If they weren't there taking up several square feet of floor space in the 'bilge' area, there would be room for more crap. Another battery, another gas tank, maybe an anchor..all things that would help quickly sink a swamped boat.
Thanks again for the replies!
 

H20Rat

Vice Admiral
Joined
Mar 8, 2009
Messages
5,199
JPTL: Have to add my two bits worth after I agree with the above advice. Those boxes filled with foam are required by federal regs regarding level flotation.

The regulations are much like mattress tags, must not be removed except by owner. The federal regs only address a new, mass market boat as it leaves the assembly plant. It absolutely does not address what the owner does to it, nor does it address home-built boats. As much as it isn't a good idea, a boat owner can legally ignore or remove the foam.
 
Joined
Jul 16, 2016
Messages
23
Smokingcrater is absolutely correct. I hope other readers know that federal requirements are built into the factory boats for safety. Please also realize that these are the minimum standards. I have read too many forums with comments about tearing out flotation inside seats, or even the entire seat, in an attempt to have more storage etc. Please check out the Boat Builder's Handbook by the U.S. Coast Guard. For Canadians, look for TP 1332E, Construction Standards.They are not easy to plough though, but be selective and use the chapter headings to avoid being overwhelmed by info. These are what the builders have to comply with. If you are modifying or building your own boat, try to do even better, especially regarding the flotation.
 

fhhuber

Lieutenant
Joined
Jun 19, 2014
Messages
1,365
I have a hard enough time with telling people to wear life jackets...

Even when a member of the local police dive-rescue team fell off a bass boat and drowned because he wasn't wearing a PFD. In calm water, sunny day... 20 ft from shore.
 

ricohman

Lieutenant Commander
Joined
Jul 30, 2011
Messages
1,631
You know, this is not a hard job to do on that boat. Even the floor is aluminum in your boat.
I would remove the carpet and cut the tops of the boxes off on 3 sides, dig out the soaked foam, and fill with new foam,
I would then bend it back with a rubber mallet and rivet a corner piece on and install the carpet again.
This could be an afternoon job on your boat. Not so easy on a fiberglass boat.
 
Top