Bow fuel tank

[pundy14]

Posted a couple of times re a rebuild of a 1980s HH 16r that has been converted to a side console/bass-boat type setup.

I've had significant issues with it sitting low at the stern as well as a leaking fuel-tank under the floor. This tank is now being cut out.

I have 3 options with regards to a replacement tank:

1 - Replace the the underfloor tank with a smaller tank (one being cut out is 90ltrs). Lighter in weight, and ensure it's as far forward as I can get it with a removable floor piece.

2 - Replace tank with a smaller one that sits at the stern, above the floor, like most boats. My issue is what kind of weight does that add to the stern given it already sits low...

3 - Look at putting a tank under the floor at the bow. Obviously that brings weight forward and the theory is that it'll help weight distribution.

My old man quite rightly points out there'd be a reason why most boats don't have a bow-tank, and I can't really argue with that point. My questions are - Are these common? What are the pros/cons? Is there any safety issue I need to be aware of? It obviously needs a really long sender hose and breathers etc right?

[chris69]

Have you thought about your transom being water logged and that’s why your transom is down in the water?

And if you look at the specs for the HH16r it only came with a 25 lt fuel capacity and weighted 390 kg and was good for 4 people so I’d be looking at what the boat weighs now it’s only got a maximum capacity of 300 kg so 90 lts of fuel plus tank weight and you have taken a chunk out of your capacity I’d be looking at a smaller tank and moving if forward a bit.

[disorderly]

Bit of a shame before you sent it in for repairs that you didnt near-empty your tank and bring along 100-150 kgs of gym weights to play around with weight distribution...

One issue may be that boats back then were generally rated for smaller motors and they were also lighter 2 strokes...

In my Noble supervee designed boat the fuel tank originally nearly 25 yrs back was right towards the back of the boat but it caused issues with being bum heavy particularly with the arrival of 4 strokes and higher H P ratings so quite a lot of water would enter through the scuppers at rest as well as issues whilst underway...

Later versions like mine moved the 180-200l Fuel tank up between the front seat and that problem is mostly alleviated..

It really is surprising just how much weight distribution changes small boat performance..

Trim tabs can help with issues whilst underway but its always better if you can balance it out as best as possible at the begiining..

[pundy14]

Have you thought about your transom being water logged and that’s why your transom is down in the water?

And if you look at the specs for the HH16r it only came with a 25 lt fuel capacity and weighted 390 kg and was good for 4 people so I’d be looking at what the boat weighs now it’s only got a maximum capacity of 300 kg so 90 lts of fuel plus tank weight and you have taken a chunk out of your capacity I’d be looking at a smaller tank and moving if forward a bit.

The boat has been completely rebuilt - new stringers, bulkheads, transom. The only original thing left is the shell and gel-coat. As part of the rebuild, we made sure there was plenty of underfloor and sub-floor drainage. I have access to to view some of the sub-floor and it's all dry and well glassed.

I'm fairly certain it's a bit of a heavy Merc 4-stroke 90hp, cutting the weight out the front, and the 16 being a relatively low sitting boat. Along with the drivers seat being set back a little compared to where it would normally sit. But I'm also guessing the 90ltr tank that stretches up the middle doesn't help either!

As you rightly point out - I'm likely pushing it for where it was originally.

I'm reaaaaaaaally hoping smaller tank, up front helps quite a bit. That way I'm not 'adding' weight up forward, but 'shifting it'.

[pundy14]

Bit of a shame before you sent it in for repairs that you didnt near-empty your tank and bring along 100-150 kgs of gym weights to play around with weight distribution...

One issue may be that boats back then were generally rated for smaller motors and they were also lighter 2 strokes...

In my Noble supervee designed boat the fuel tank originally nearly 25 yrs back was right towards the back of the boat but it caused issues with being bum heavy particularly with the arrival of 4 strokes and higher H P ratings so quite a lot of water would enter through the scuppers at rest as well as issues whilst underway...

Later versions like mine moved the 180-200l Fuel tank up between the front seat and that problem is mostly alleviated..

It really is surprising just how much weight distribution changes small boat performance..

Trim tabs can help with issues whilst underway but its always better if you can balance it out as best as possible at the begiining..

I know I probably should have played around a bit, but I'm just too worried about the fumes that I can smell under-floor. For my own safety and piece of mind, I just wanted it out and will have the cavity converted into storage.

I like hearing that feedback re moving your tank to the seats. I'm really hoping getting rid of this 90ltr tank, and putting a much smaller one up the bow will help quite a bit!

One of my concerns is the filler cap is located at the stern. I just don't think I can still use that to fill the tank so far forward as the fall of the hoses wouldn't be enough for gravity to do its thing. I guess the whole throw another thousand to get filler removed and patched up comes into play!

[Dignity]

You may not need to move the tank all the way to the bow to help equalise things. And your old man is right in one respect, the bow is where the most bounce is. I'd take the old tank out, use a portable tank and put it further forward, put extra weight up there, buy several of those 15 litre water bottles that people take camping, buy in woolies etc and add that to where the fuel tank is going to be and do a few test runs. There's nothing worse than doing a fix only to find you created another problem.

[pundy14]

You may not need to move the tank all the way to the bow to help equalise things. And your old man is right in one respect, the bow is where the most bounce is. I'd take the old tank out, use a portable tank and put it further forward, put extra weight up there, buy several of those 15 litre water bottles that people take camping, buy in woolies etc and add that to where the fuel tank is going to be and do a few test runs. There's nothing worse than doing a fix only to find you created another problem.

Yep - I think that's sound advice.

Reckon I'll take the current tank out. Seal the cavity so it can at least be used for storage. Get a much smaller tank (portable) and play around with where I put it. If I find the right shape, there's no reason it can't actually sit at the very front of the cavity from the old tank anyway!