Securing portable fuel tank to aluminum floor

[BuffsBoat]

I'd like to balance the weight out in my Zodiac Classic. I want to put the fuel tank (and maybe even the battery) towards the bow. Any suggestions for securing it to the floor? I was thinking of cutting a rubber mat to size, and adhering it to the bottom of the tank. That might prevent it from sliding. But I'm sure it'll still bounce like crazy. Maybe use bungee cords somehow secured to the floor rails???

Any thought would be very much appreciated

[spartacus]

If it has floor rails it must have the aluminium floor? Zodiac sell a kit with strap fasteners that locate in the floor rails and a plastic fuel tray for the tank to sit on. The strap on the fuel tray doesn't look up to much, but at least stops it sliding about. Details here: Zodiac Marine - Accessories - Fuel tank support

The strap kit is Z1226.
http://www.ronhalemarine.co.uk/super...p_Tie_Down_Kit

[Redrock]

Hi

When positioning your fuel tank and battery, plese bear in mind that the majority of movement on a boat happens at the bow. The stern, where most are positioned, stays relatively stable as it is the pivot on which the bow bounces. The wave action at the bow will stir up your fuel and battery fluids quite a bit.

If you want to go ahead, your Aluminium floor does not need to be watertight, so you could easily fix some straps to the bow section. I used to put my tank in the bow of my Airdeck and secure it to the lifting davits with bungee cords! Crude but effective, without any drilling.

[treerat]

My Yam had a 3 section floor - I was able to move the section that had the tie downs built in from the stern to the bow and use the ones supplied - is your floor sections or one piece?

[Sharkbyte]

Zodiac's ply floors also have rails. Besides which, the bow section on those boats spec'ed with an aluminium floor is ply anyway.

Personally, I'd say putting the fuel tank up-front is a bad idea. The strain on the fixings if your out in sloppy conditions will be huge. I've snapped the webbing straps on my bow bag before now; a full fuel tank strapped down will probably tear itself free.

As for the battery. Forget it, IMO.

[BuffsBoat]

Originally Posted by Sharkbyte

I've snapped the webbing straps on my bow bag before now.

Ouch! That don't sound good!

What happened, and how can I prevent it from happening to me???

So the general consensus seems to be to leave the fuel tank at the rear. It seems like an awful lot of weight in the back. The 15hp motor weighs around 120. I'm a hefty guy, and the fuel tank adds even more weight! The only thing towards the bow will be my young daughter (hardly enough to balance the load). Do you all think this would impeded performance or damage the boat? Could the weight disproportions be counteracted by adjusting the trim?

[Sharkbyte]

Not a big problem - easily repaired - but it gives you an idea of the forces at work at the bow when it cuts up a bit rough and you're maintaining a decent speed.

The bow bag contains our anchoring gear and probably weighs 20kg, or so.

Why not stick the fuel tank amidships? We've had no problems with ours fitted just infront of the console. Our battery (60ah) is fitted by the transom.

I know that getting as much gear as far back as possible is best for ultimate speed, but to be honest, for anything other than calmish waters, you can't beat spreading the load slightly.

The boat is as solid as a rock, and very predictable, with never a hint of flipping even in the strongest headwinds and lumpy conditions.

[kelson]

Interesting comments regarding the movement of batteries and weight forward. I certainly don't agree with those who think that moving the gas tank and battery forward is not a good idea. My futura mk2 gets run out to surf spots through overhead surf. I also use it to pull wakeboarders and hydrofoilers. Moving the weight forward (not necessarily all of the way to the bow) has more effect on the handling of the boat than my trim tabs do. Tail heavy sibs like to stand on end when dealing with large waves and full throttle hole shots.

I have included a few shots of my set up. At first I had the large plastic gas tank strapped down to second wooden floor section. The footmans loops are bolted down with the nuts recessed into the bottom of the floor. I had no problem with the full tank coming free or that floor section pulling up. Most tank straps are polypropylene. If you have trouble with the straps breaking replace then with nylon. Nylon straps are stronger and more UV resistant. Nylon tubular strap is ridiculously strong. Strapping down the tank is not a big deal.

I moved my tank under the console bench (modded the bench to fit) and that freed up floor space. The move back onto the front aluminum floor section did not significantly change the boats handling. When I purchased a custom aluminum tank I had room to move my battery from where it was strapped under the bench seat to the same spot under the console. Very nice hole shot with this lay out! No excessive bow rise. I also still use my large plastic tank for extended trips with it strapped in on the wooden floor section. With everything in place and full the boat is actually a little bow heavy, but I run like that with a full load of gear and that balances everything out.

Have not had any problem with the gas getting sloshed too much or the battery failing (but I do run an AGM battery that can take abuse). My zodiac did not handle well until I made the move to get weight forward. I would never run with a tank and battery at the back of the boat. To each his own!

[kelson]

As far as fastening methods go. I used stainless steel footmans loops to strap down my tanks to the wooden floor board. They are bolted through with the cap screw and washer in a counter sunk hole on the bottom of the wood floor section. I filled over the bolt cap with epoxy to avoid any chafing. I ran with my tank strapped down to the aluminum section by fastening footmans loops attached with stainless steel pop rivets. I had some concern about the loads that this placed on the aluminum top sheet, but it didn't crack or fail over a two year span. When I moved the battery and installed the custom tank I used an aluminum plate to span the floor, bolted that to backing plates that are inserted into the sides of the floor section with the cap off and these plates key into the side rails. Very strong and secure. The photo below is how I did the same technique when preparing to mount my ski pole. Probably total overkill for most uses, but I throw it out there for what it's worth.

[Peter_C]

Kelson, your gear is not in the bow, but midship. The OP was saying to move the gear into the bow. I agree with others this is not the best place for heavy mounted objects, and specifically chose not to put my fuel tank and battery in the bow for fear of tearing the boat apart. Midship would be a great location if running a center console or using some kind of seat setup, but not so good if using a tiller and sitting on the tubes.

FWIW I have a 6 gallon fuel tank mounted on the port side stern. No problems, but we tend to load the boat with heavy dive gear most of the time. People will want to stay back further in the boat, as the bow is the roughest ride.

[treerat]

Originally Posted by kelson

My zodiac did not handle well until I made the move to get weight forward. I would never run with a tank and battery at the back of the boat. To each his own!

My Yam had the tank in the same position as shown in Kelson's pic - so not really in the bow.

Used her in some good surf and pulling toys around, wouldn't have moved it back again, handles so much better.

[kelson]

Peter c

The OP referred to moving the weight "toward the bow". He didn't say he would bolt it to the very first wooden section...

I rode with the big plastic tank strapped down to the second wooden floor section and it wasn't a problem. Now I just do that when I need the range. Just have to make sure the boat is properly inflated!

Nice thing about sibs is that everyone gets to customize their own layout. Lots of ways to do things.

[Peter_C]

Originally Posted by kelson

Peter c

The OP referred to moving the weight "toward the bow". He didn't say he would bolt it to the very first wooden section...

You are right, and my reading comprehension needs work.

Originally Posted by kelson

I rode with the big plastic tank strapped down to the second wooden floor section and it wasn't a problem. Now I just do that when I need the range. Just have to make sure the boat is properly inflated!

When I was trying to figure out where to put my fuel tank and battery, I went under the boat and looked at the hull. Since it is a 1992 boat that has sat on it's trailer most of it's life it is clear to see the pressure points. One of them is the 2nd board pushing hard on the floor where it meets the first board. Therefore the only weight I permanently keep up front is the milk crate with anchor and rode.

Originally Posted by kelson

Nice thing about sibs is that everyone gets to customize their own layout. Lots of ways to do things.

Definitely! Mine has seen a couple of revisions so far as my needs have changed. It just went on a big diet for beach launching, also making most everything inside removable to be hand carried up the beach.

[BuffsBoat]

Originally Posted by kelson

Peter c

The OP referred to moving the weight "toward the bow". He didn't say he would bolt it to the very first wooden section... .

That's my bad. I would never consider moving it to the bow. I did mean in the middle.

[kelson]

Buffsboat,

Actually Peter C and I are pretty much on the same page here. Every boat is a little different and each set up has its pros and cons. Peters post refers to the fact that he runs a lot with dive gear. Throw some weight up front in the boat like that and you end up balancing out the trim without tabs or moving your battery or gas tank. I used to be set up for mostly beach launches, but I've gone the other way and now it isn't easy to take everything out of my boat at all. I also have less open space than a tiller set up, but I'm comfortable in my suspension seats while towing people around all day or blasting out to surf. It all depends on what you are going to be doing 90% of the time. Since I mostly surf and foil with my boat it is set up for that. While I didn't have any issues with the second wooden floor section chafing the boats floor material, that may be a real issue in a different boat. I inspect the boat regularly to make sure my mods are holding up. I moved that forward tank back under the console bench to free up floor space, but it was working for me up forward like that until I could bring the battery forward too. In the end you want the boat to handle well and fit your needs. The bow rise on my futura was extreme on full throttle starts and the boat really was a bit scary coming off the top of large waves. I was ready to sell the boat after the first few runs, but now I have a stable platform that I am confident in. In the end experience will guide you and I'll bet your set up will change over time. Have fun!

[mister p]

Simple way to fix a tank in a vessel with removable floor panels (ie a SIB). Before fitting the floor panel onto which you wish to secure the tank, lay a webbing strap ( of the ratchet strap variety) widthways first. Fit the floor. The ratchet strap is now secured without drilling etc. Once inflated the sponsons secure the strap. Once the tank is ratcheted down it will not move.The sponson pressure prevents the floor bowing up and the whole system is non invasive. A towel under the tank softens the "fizz" but is not essential.

[Peter_C]

Having a wing mounted on the outboard also changes the balance of the boat. I have a Stingray on mine. Keeps the bow down, and it planes at 12 mph.

Lots of options, you just need to decide which one is right for you. No matter what your setup is, it is best to keep the people back as far as possible.

My tank was originally mounted with these, although just screwed into the floor they have held up to abuse. The dissimilar metals react a little but not bad. Put some anti-sieze on them upon assembly. Then I used a cheesy ratcheting strap set from China that I figured I would throw away, but with some WD-40 they keep living with only surface rust. I just cut the tie down the length we needed.



I also have four of them mounted on the second board that my tag lines attach to so when returning from diving we clip our gear off to them before reboarding. I put a D-ring on my partners 24lb weight belt so she doesn't have to lift it into the boat, but instead she can clip it off and let if drop. So far they are all solid with no pull outs. They could always be thru bolted if protected on the bottom with nothing in the way.

The battery should definetely not be at the back of the boat. Taking water over the stern leaves the battery box getting wet (Seems to happen often to me *shrugs*). I moved mine forward just for this reason alone. It is also going to get put into a sealed tower here within a couple of weeks.

Kelson, there are many times when just out cruising I wish I had seats and a steering wheel like your boat has. Way more comfortable than sitting on the tube and twisting the throttle for over an hour. We wind up taking turns driving and lots of breaks. For diving out of though floor space is at a premium...there isn't any LOL

[BuffsBoat]

Guys...these are GREAT posts, and great suggestions! Each one is valid. I guess I will follow the advice that seems to be common in all posts.....Try out various combinations, and use what works best for me

Thanks for all the insight!

Gtreat forum!

[jyasaki]

Pete; How big is that D-ring? Looks huge.

jky

[Peter_C]

Originally Posted by jyasaki

Pete; How big is that D-ring? Looks huge.

jky

Very small actually. I would guess the pad eye is about an inch.