BB3 Sponson modification

James Dalton

James Dalton

Member
Hello everyone. I have been lurking around this site for a couple of months now and have heard a lot of good things about Devlins BB3. I decided that this would be my first build. Never built a boat before but with the great plans that Devlin produces and the wealth of info from this site I think I can tackle this. I'm real excited to get started.

In the meanwhile I am building a scale model of it. Its helping me envision what the real build will be like. Its also getting me thinking about different mods I can make to it. One that I am really interested in making is to the sponsons. I wanted to create a little more storage so I am thinking about splitting them in half and creating an opening much like the one in the bow instead of access holes. I am thinking about storing the battery on one side and maybe a repair/parts kit and the necessary USCG items in the other. I don't want to put any more weight in them then what the battery may weigh. I know that this will reduce the floatation, but that only comes into play if the boat is starting to go under (God forbid!). I am planning on purchasing a 25-30hp 2 stroke so the weight of the motor should be around 120lbs give or take. I have included some photos of the model to give everyone a better idea of what I'm thinking. I wanted to get everyone's opinion of what this might do to the "ride" and stability and any other issues that I might not be thinking of. Any and all comments are welcome. After looking around on this site I trust the opinions and advise of everyone here. Thanks for your input!

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Models are a great way to figure things out. That's good. As for removing flotation, don't do it. What you show is similar to the Scaup configuration but Sam planned for adequate flotation. What good does the flotation do if it's not enough? Not enough good that's what. There are other ways to to integrate your battery and storage needs. You can use the side storage bin just in front of where you are thinking of putting it now. You will have plenty of storage room as designed. If not you need a bigger boat. Many builders in the beginning stage fret over storage and seating. Don't fall into that quagmire. Spend your upfront time on the building process and less on the final bells and whistles. In the end it will all come together and you will be glad. Again, don't remove flotation, it isn't called for.
 
Setting the safety aspect aside as Eric covered it.

Putting a battery in sponson adds an additional, what, maybe 40 lbs to the transom weight plus a tool kit, etc on the other side. This boat wasn't designed for that much weight in or on the transom and will perform poorly. I put my battery up in the forward storage compartment with a custom aluminum gas tank.

The BB3 is a great boat but can be sensitive to balancing your load weight forward and aft. Don't put any more weight than you need in the aft end and you will have better performance.

Pete
 
Gotta agree with the others on this, removing floatation is not a good idea. Also, putting the batteries that far aft is adding weight in the last place your need it, the stern. I would re-think your idea.
 
Since a garden tractor battery is all that is needed, I don't think weight is a big issue. I wouldn't want an inclosed battery compartment in the back because it has to be vented. Take away the floatation and add a vented compartment and it's trouble.I had my battery in a carrier with plug in wiring just in front of the sponson and never realized any performance issue and it was a big marine battery. The sponson floatation is what floats your motor if you sink. If mine sunk, I wouldn't want to be walking a titerope till help arrived. Some guys have foamed in a plastic container with kayak waterproof lids into the sponson for watertight storage of paperwork and cell phones. Think about putting a couple wide 1xs front to back under the plywood so a big fluffy guy can stand on them to pee without cracking the plywood. I have never wanted for storage in my BB2 even with two guys a huge lab and more dekes than I want to pick up at the end of the hunt.You could extend the sponson into the boat for your storage if you must and I thought about doing that to give a little deck in front of the motor so I could make a good hatch cover. I use a long shaft so I could still tilt my motor...I think...
 
Guys, this is great! I knew I could count on you helping me think thru this. I wasn't sure of how much storage I would have really, but it sounds like I should be just fine. The one major question I had about making this mod was about the extra weight. That answers it then. I don't think I will follow thru with this mod.

Pete - I was wondering if you could give me some more info on the fuel tank you have in the front. From reading past posts I understand you have a 9 gal tank. Do you have pics of it being installed or even already installed? How much storage do you have now in the bow?

Anyone else install a built-in fuel tank? What other mods have people done to their BB3? Pics? More storage ideas? As you may be able to tell, I am kind of a neat freek. I'm not planning on loading the boat down with a bunch of crap that I will never or hardly use. I just think its better to know were everything is and that everything have a consistent place to be put. Plus its just safer to have everything tucked out of the way when under way.

Again, thanks everyone!
 
I am kind of a neat freek. I'm not planning on loading the boat down with a bunch of crap that I will never or hardly use. I just think its better to know were everything is and that everything have a consistent place to be put.
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That could very well be something I'd write.

Let's see, my gas tank is in the back port side bin along with lifejackets. The back starboard bin is where my battery, lights, rope, hat for cold rides, diet Mountain Dew, and other odds and ends go. The other storage bins are for decoys. I can put close to a dozen in each bin depending on their size. The front storage holds my tree pruners grass shears, and more decoys. The lawn tools are mandatory equipment in my book as they allow me to quickly cut whatever cover is in the area and camo my boat. Grass is a base coat but I use whatever the surrounding vegetation is whenever possible. I keep a paddle and a pole/hook off to the side of the cockpit. My partner, dog, and dry bags go in the cockpit area.
 
James,

Yes, the gas tank is approximately 9 gallons and is installed up against the forward bulkhead and takes up about 9" of the forward end of the forward storage compartment. The tank is basically in the shape of the hull on the bottom and has a fill and vent on the top that comes out through the front deck. I don't have the pics of the installation on this computer and I'm not sure where the pics are or I would rescan them in. I got the gas tank made at RDS Aluminum in Perry, Florida in 2003. At that time the tank cost $175 plus another $17 in freight. If you want to persue this type of tank I can give you the contact information and the Part Number that was assigned to it so you can duplicate it. The design and part number are a little different than the original Pete Markantes design from which it originated.

The only difficult thing about this tank is the long run from the tank back to the motor. It requires a lot of bulb pumping to get the gas going if it has sat for a long time. Then again part of the problem could be the fuel/water separator filter that I installed next to the gas tank on the inside of the forward access bulkhead. Once the gas is flowing I usually don't have much of a problem the rest of the season - just initially. I like this tank and where it's installed - keeps it out of the way of everything else.

Pete
 
Here's a pic of the original tank, RDS Part #59887.
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I use the Perko combination fill cap and vent.
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Pete McMiller, out of curiosity, can you describe the modifications from the original?
 
Hi Pete, been a while.

1) I changed the overall height from 12" to 11" which changed the dimension from the top to the first angle from 6" to 5". The original design was too tight to the deck and even at that I think I could have reduced it to 10 1/2" to facilitate a smoother installation of the Perko unit.

2) I increased the forward to aft dimension from 8" to 9". Basically to retain the approximate 9 gal. capacity.

3) I moved the Vent and Fill fittings to a port/starboard orientation (respectively) instead of a forward/aft orientation as indicated on your drawing. I put them in the same line as the PU - 2" from the aft edge of the tank with the vent inboard of the fill and 18" from the port edge. Center to center was 1 9/16". This accomodated the same (I think) Perko 1319 series Combination Fill/vent. I didn't want the fill cap opening facing forward incase it didn't latch and would flip up in transit.

The new Part Number is 62896 and is under my name.

When I installed it I put in permanent studs from the flotation compartment to align with the mounting holes on the tank. In addition, I glued a strip of 2" wide closed cell foam on the aft bottom edge of the tank to contact the bottom of the boat with a bit of cushion. Don't know if that made a difference other than peace of mind.

Clear as mud?

That is a great installation picture.

Best,

Pete
 
Pete, I completely agree with your changes and would incorporate in any similar build.

At the risk of hijacking the thread, are folks hearing any buzz re: ethanol and gas separating and causing problems with outboards with built-in aluminum tanks? Our local marine mechanics are recommending keeping tanks full and using fuel stabilizer as a preventive practice. This has been SOP for me from the beginning but I'm curious about what others are hearing.
 
One way to do it is to buy a square red 6 gal plastic tank, build a shelf, put the tank on the shelf. The space under the shelf is a nice neat place for the anchor. That is what I did and I'm really glad I did it.

May I recommend that you take a look at the Cackler design? It pretty much is the way that you want the sponsons and it is the same size as the BB III.

Good luck
 
Pete, I,ve heard grumblings about Ethanol. I think the alcohol attracts water and I have heard it seperated. I wonder how long it takes to do that?
 
Thanks! Great photos of the tank. I looked up the company online and found a phone number and email. Thanks also for sharing both of your stock numbers for the tanks. I will be contacting them and asking for a quote on your numbers.

When I get started on the build I will post photos and keep everyone up to date. Hope to start it with in the next month.

Again, thanks to everyone for their great advice. I know where to come with any problems!

Jim
 
Yes and Yes. Several of the boating magazines have run lengthy articles on that phenomenon. Long and short is keep your tank full and use a stabilizer all the time. I think a fuel seperation problem caused a burned cylinder and thus the ultimate demise of the 90 hp Johnson that was on the stern of the old and greatly missed "Marsh Pig". Don't think you hijacked the thread but this is a subject that needed to be discussed.

Best,
Harry
 
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