Bow Deck Rubbing on hull - slight detent created

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Tin Man

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I am at the beginning stage of planning a small bow deck so I can a TM. and one group 27 battery. This deck is to be created above the forward-most crossmember seat/bench and use the rear vertical section as the aft wall of the deck (pic).

First step was to remove the front section of deck and take a look under the forward-most cross member/seat. Previous owner stated he added two 50# led bags under this area to assist boat getting on plane. BTW...Boat performs great with this added weight.

I found the the lead bags and removed them. I also found an alum bracket he fashioned and riveted to one stringer and to a front alum factory panel. I'm assuming this bracket was installed to stabilize and trap bags up forward (pic).

Now after partially removing the forward section of the forward-most floor section (it's alum), I noticed that the floor has been rubbing against hull and has created two issues: 1) rubbing and weight of standing on floor has created a detent in hull (see pics). When I rub my fingers over this area I can clearly feel this detent. 2) Alum hull appears to be wearing down (pics).

My concerns: 1) detent may cause issues 2) if floor is left rubbing, it will rub through the alum hull. Hull and sides are 0.065" thick.

Floor is factory. Forward-most section (one discussing here) is alum covered in vinyl and rear floor sections are 3/4" plywood covered in vinyl.

My plan was to add a battery under the forward-most bench (pic), as I wanted weight as low as possible. I would have to build a sub-floor in this area (pic) to accommodate the battery. OR...I could install battery on top of the bench since it will be covered under the TM deck I am building (pic).
 

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From the pics I don't think I would worry about the chaffed area as it is, but I would fix it so it doesn't become a bigger problem. Putting the battery lower still seems like a good idea.
 
I was thinking of using door edge molding along the edge of the floor where it is rubbing. It would be a simple and inexpensive fix that should last a few years.

Thoughts on this fix?
Other ideas?
 

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If the foredeck is just resting on the tapering hull and the edges are as thin as they look, I am not surprised by the wear and deformation of the hull. Match what was done on the battery shelf, including the gap, and you should be in good shape.
 
I was thinking of using door edge molding along the edge of the floor where it is rubbing. It would be a simple and inexpensive fix that should last a few years.

Thoughts on this fix?
Other ideas?

If the fit is tight enough to dent the hull as is, you will never get the floor back down where it was with the added thickness of those strips in there, and it doesn't do anything to address the issue of the floor being supported around the edges. I would add a couple of stringers to support the floor across the middle.
 
If the foredeck is just resting on the tapering hull and the edges are as thin as they look, I am not surprised by the wear and deformation of the hull. Match what was done on the battery shelf, including the gap, and you should be in good shape.
I have not made a battery shelf. That project brought me to my current dilemma, when I lifted the forward portion of deck.
 
If the fit is tight enough to dent the hull as is, you will never get the floor back down where it was with the added thickness of those strips in there, and it doesn't do anything to address the issue of the floor being supported around the edges. I would add a couple of stringers to support the floor across the middle.
The deck is approx. 7-10" from bottom of hull. Where would stringers attach to bottom of hull and to underside of deck? Material? Would they run lengthwise to hull or perpendicular?
 
The floor is supported at the front end by the sheet metal face piece of the front bench. There is an approx. 2" L bend at bottom of the face piece that supports the floor. Face piece is riveted to the floor and then face piece is riveted to bench. I'll take a few pics showing this section.

I did notice that the floor has a gap of approx. 1/4" near the front portion. The section that rubbed is flush against hull. Perhaps the floor needs to be trimmed where it is rubbing so there is a small gap (to avoid rubbing on hull.) Then the trim rubber I posted above could be used.
 
I'd remove the diagonal brace and leave it out of the equation. Depending on how high the battery sits on the shelf it's now sitting on, I'd put a straight edge across the gunnels and see if you can leave the battery where it is. If it clears I'd mount it where its sitting. You won't gain a whole lot by mounting it lower. My next question would be how much did the weight that was there add up to versus the battery weight? The added weight might make too much of a difference causing plowing issues. I'd set an equivalent amount of weight in place for both the battery and trolling motor plus some for the deck it will set on and take your boat for a spin to see if there are any adverse effects from the weight. You might end up having to distribute weight before proceeding further. Something else to consider, you don't necessarily need to set the battery on the floor. You can also suspend the battery if you put the trolling motor deck in place first if you place it across the gunnels. Basically you'd be making a shelf underneath the trolling motor deck to place the battery inside. This would let you have more support by distributing weight across a bigger cross section.
 
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I'd remove the diagonal brace and leave it out of the equation. Depending on how high the battery sits on the shelf it's now sitting on, I'd put a straight edge across the gunnels and see if you can leave the battery where it is. If it clears I'd mount it where its sitting. You won't gain a whole lot by mounting it lower. My next question would be how much did the weight that was there add up to versus the battery weight? The added weight might make too much of a difference causing plowing issues. I'd set an equivalent amount of weight in place for both the battery and trolling motor plus some for the deck it will set on and take your boat for a spin to see if there are any adverse effects from the weight. You might end up having to distribute weight before proceeding further. Something else to consider, you don't necessarily need to set the battery on the floor. You can also suspend the battery if you put the trolling motor deck in place first if you place it across the gunnels. Basically you'd be making a shelf underneath the trolling motor deck to place the battery inside. This would let you have more support by distributing weight across a bigger cross section.
I never had a TM battery up at bow. I just placed the battery box there to see how it would fit.

First step is to modify front deck to keep it from rubbing.

My thoughts are to grind away some of the alum edge of the floor that is rubbing. It is a bout a 15" section that needs to be grinded.... remove approx. 1/4"...enough space to clear hull sides and fit trim molding. Then, add 1.5" or 2" angle alum to act as braces to underside of floor to add stiffness since floor/ will no longer be resting on sides of hull.


I am now considering placing battery box on front deck inside an ice chest that fits a battery box. The added angle alum to underside of floor should stiffen floor enough to accomodate this...plus floor is designed for passengers to stand and casting, even though it is at floor level.
Ice chest footprint would spread load. I can add a TM plug to side of ice chest and wiring from battery to plug would be a very short distance. Ice chest would be strapped to bow seat.

Thoughts?
 
I'm not fully understanding from the pics. Was that aluminum deck section just wedged in without any support underneath? I agree with you about trimming it back so it doesn't rub. I think you would still have the problem if you just added the door edge. Then the quandary seems to be how to support that section. Maybe some combination of the suggestions to add braces from the stingers, rivet angle brackets along the hull, and hangers from bow cap, IDK.

If the 3/4 ply decking running up to the bench is solid, another option would be to mount the battery there and extend your new bow deck back to cover it, or make the bench wider to cover it. Of course the big downside is you lose deck space.

Edit: I just saw your other TM post and now think I probably misunderstand what is going on with the problem deck section . So, I'm likely all wet in my last suggestion.
 
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Attached is a rudimentary drawing of the front floor section. I understand...pics are challenging to understand. I'll take more pics after I remove floor.

Question: Not sure why Alumacraft decided the forward section floor should be made of alum and the middle and rear floors made of 3/4" plywood??

As you can see from drawing...the floor is supported by the two fore and aft tabs (2" angle at mid bench and fold tab of forward bench). The floor was rubbing on sides of hull...It appears the sides rubbing/hitting sides of hull also added support for the floor.

Thoughts are to grind down floor in the two areas where it is rubbing. These are abut 13" sections on both starboard and port sides of floor. Add trim molding just for appearance and prevent vinyl floor from lifting.

After griding away sides of floor so that no part of floor is rubbing on sides of hull, floor may flex. My thoughts are to add three sections of 1.5"x1.5"x1/8" aluminum angle to underside of floor. This should stiffen floor and remove any flex. Does it matter which direction these angle pieces are installed (fore-aft OR starboard-port?

Thoughts on other ways to support floor?

My take: Alumacraft thought that the fore and aft tabs were sufficient to support the floor....they just did not trim the floor correctly.
 

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Pics with floor removed.....

Nice to see....Alumacraft added stiffener ribs to underside of floor!

Now I think I may be good with just grinding down edges of floor where rubbing and re-install.
BTW.....alum angle for floor supports (fore and aft) appears to be approx. 1/8" thick (0.115) for mid bench support angle and 3/32" (0.08) (for forward support angle.
 

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Here is what I did on my last two boats and it works wonderfully.

You can’t see the construction, but what I did was to make a small bulkhead out of plywood and shimmed the battery box to where I wanted it and encased the box behind the bulkhead in 2 part expanding foam. The support for the battery box is a T shaped plywood section that conforms to the shape of the hull and brings the battery to the required height. The foam and the T frame both tale the weight of the battery and this prevents any damage to the hull.

The bulkhead is located where the floor ends and is covered by the deck which has the trolling motor mounted to it.

This puts about 150lbs as far up front as possible and balances the boat with a 25hp motor and my 300lbs in the back.


If were me I would remove the front seat and go this route.


86280-73f14e123bd814f2f43db64b4937313e.data
 
Here is what I did on my last two boats and it works wonderfully.

You can’t see the construction, but what I did was to make a small bulkhead out of plywood and shimmed the battery box to where I wanted it and encased the box behind the bulkhead in 2 part expanding foam. The support for the battery box is a T shaped plywood section that conforms to the shape of the hull and brings the battery to the required height. The foam and the T frame both tale the weight of the battery and this prevents any damage to the hull.

The bulkhead is located where the floor ends and is covered by the deck which has the trolling motor mounted to it.

This puts about 150lbs as far up front as possible and balances the boat with a 25hp motor and my 300lbs in the back.


If were me I would remove the front seat and go this route.


86280-73f14e123bd814f2f43db64b4937313e.data
That looks great! I thought of something similar where part of battery is as low as possible and a portion is above deck/floor level.

I see that the bow area becomes steep and narrow as you move forward. How far is the battery off the hull or is it touching? I can't tell if that's the charger (NOCO) in the pic and also can't tell if battery box has been cut down.
 
RBW's approach is very cool. I was thinking (always dangerous) if you could fit your battery below the small front bench, then the bench top would be kind of a dry storage shelf above the battery and below your new bow deck. Might not be enough room.
 
RBW's approach is very cool. I was thinking (always dangerous) if you could fit your battery below the small front bench, then the bench top would be kind of a dry storage shelf above the battery and below your new bow deck. Might not be enough room.
Yes, his set up is great. I will use the area above small bench for storage after I create a TM deck and face.

One option I have been considering is to place the battery at very front of floor deck. After finding the stout floor stiffeners and trimming floor so it doesn't rub, I feel confident the battery (in a small ice chest to spread load) will be secure and well supported (the ice chest is just to spread the battery weight some). Ice chest will be strapped to small front bench and the battery fastened to floor of ice chest. At least that's what I'm thinking right now. Although I do like the idea of battery below small bench as what RBW has done. I'll do some more planning and see what I come up with. Need to get the floor/deck completed.

Attached are pics of floor after grinding away some aluminum; between 1/4" to 1/2" along starboard and port sides was removed.
I will now add some thin rubber over the area where it was previously rubbing to clean up that area (aesthetics) and extend rubber about 1" below the new floor edge. This will be to protect hull when the floor flexes under heavy load of passengers. I will also be using the trim molding along the edge of the floor sides.
 

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That looks great! I thought of something similar where part of battery is as low as possible and a portion is above deck/floor level.

I see that the bow area becomes steep and narrow as you move forward. How far is the battery off the hull or is it touching? I can't tell if that's the charger (NOCO) in the pic and also can't tell if battery box has been cut down.
The forward most corners are about 1/2” from the hull so it is fully enclosed on the bottom.

The T section was placed in and references on the first rib which you can see in the pic. It is behind but screwed to the piece that makes up the bulkhead you can see.

This was important to have in place as you need the weight of the battery to keep the foam from lifting it out of position.

That is another reason for doing small pours, and also so you don’t wind up with a huge mound you have to cut down flat. After the foam cured I cut it flat/level with a power hacksaw blade. Then I put Luan plywood that was epoxi sealed down for a flat surface, then carpet.

ETA: Ran out of time earlier.

The NOCO is the battery box brand and it is not cut down, just buried in the foam. As mentioned the front two corners are near touching the hull and the rear two corners are probably 6" or so off of the hull. My charger is not in the pic but it rides to the right of the battery and slightly forward with my anchor, life jackets and rope.

I think I can sneak the battery out when/if I need to replace it without removing the deck. I think.

Ive also drilled and added a grommet to put the wires under the deck so their not exposed and finished (Mostly the floor since that pic was taken.
 
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The forward most corners are about 1/2” from the hull so it is fully enclosed on the bottom.

The T section was placed in and references on the first rib which you can see in the pic. It is behind but screwed to the piece that makes up the bulkhead you can see.

This was important to have in place as you need the weight of the battery to keep the foam from lifting it out of position.

That is another reason for doing small pours, and also so you don’t wind up with a huge mound you have to cut down flat. After the foam cured I cut it flat/level with a power hacksaw blade. Then I put Luan plywood that was epoxi sealed down for a flat surface, then carpet.

ETA: Ran out of time earlier.

The NOCO is the battery box brand and it is not cut down, just buried in the foam. As mentioned the front two corners are near touching the hull and the rear two corners are probably 6" or so off of the hull. My charger is not in the pic but it rides to the right of the battery and slightly forward with my anchor, life jackets and rope.

I think I can sneak the battery out when/if I need to replace it without removing the deck. I think.

Ive also drilled and added a grommet to put the wires under the deck so their not exposed and finished (Mostly the floor since that pic was taken.
A drawing to go along with the pic would be great. I'm trying to imagine it based on your discussion. A drawing would help considerable. Ex., When you say a T, I think a T would go down middle of hull but that can't be as the battery is in middle.
 

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