Monsun 31 Water Tank

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mcmurton
Bottom Sanding Grunt
Posts: 4
Joined: Sat Mar 16, 2024 8:27 am
Boat Name: Moonbeam
Boat Type: Hallberg-Rassy Monsun 31

Monsun 31 Water Tank

Post by mcmurton »

James and others -
I'm getting started on an integral water tank under the v-berth. James, I believe you may have done a similar install for Bo on his Monsun. I plan to move the bowthruster battery and cut out the small "wall" behind the battery as well as the panel on whi the battery sits. The forward and aft walls of the tank will be where the two brown wooden transverse bunk supports are. I'd rather work around these, or use them as supports if the geometry work out, as I don't want to "un-do" something if it's working and potentially create more tasks for myself later. I'll have to dismantle and later reinstall the footwell woo
Monsun fwd.jpg
dwork and work around the bowthruster.

Question: Should I use 1708 for tabbing since I'll be reinforcing the Divinycell panels with 1708? Or can the tabbing be something a little lighter (e.g., leftovers from other projects)?

James: In Bo's boat, do the v-berth cushions lie directly on top of the tanks and access hatches?

Mark
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atomvoyager
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Re: Monsun 31 Water Tank

Post by atomvoyager »

Mark
I generally use 1208 for tanks rather than 1708 since it conforms and saturates easier. You need to judge for yourself how thick and wide of tabbing you need based on hull thickness, size of tank, length of unsupported areas, etc. For example, you might prefer to use two layers of 1208 or try to get by with one 1708 or 3-4 layers of 8-10 oz cloth. The cloth is convenient in some areas because it conforms most easily around corners.

At 14 minutes in the video linked below you see the shallow locker on top the tank and explanation why I build it that way. The bunk cushions do lay directly on top the bunk top and its plastic hatches. Or as I did in my previous tank video, make your own flush hatches from the plywood you cut out of the bunk top to create the locker access. The plastic hatches are somewhat flimsy anyway and since they stand proud you might notice a lumpy cushion if using thin mattress foam of 3 or 4" thickness.

https://www.youtube.com/watch?v=fnySnyNT1TI&t=5s
mcmurton
Bottom Sanding Grunt
Posts: 4
Joined: Sat Mar 16, 2024 8:27 am
Boat Name: Moonbeam
Boat Type: Hallberg-Rassy Monsun 31

Re: Monsun 31 Water Tank

Post by mcmurton »

Thank you, James. Your video was the inspiration for this project...the view of Bo's boat at the end clinched it!
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