Trimaran Interior Space vs. Bulkheads

A couple follow ups..

1. why would you not want a double bunk? Just sayin..

2. there needs to be a seating area; typically your bunk area near the galley might double as convertible bed, but then you have zero privacy .. my boat and enough space, I make the walkway off the side of the galley (port), then a settee to starboard and the entry to a double bunk also to port .. the settee can be convertible

There is a massive thread here that has hundreds of multihulls and probably a few GAs. Those could also help you greatly.

Multihull structure thoughts..

 

Also, google or ask an AI bot for 42 foot trimaran general arrangement drawings..

 

Here is a crude finger sketch:

I would separate the two staterooms. Shrink the head width down on the bulkhead end and add the two single bunks aft. Try to sneak in a settee off the starboard wall. The chart table can be next to the galley on a triangle. You’ll need to reinforce the for’d BH to allow for an offset door, but a double bunk is way nicer and the slide in settee is classy and could be made into a convertible bunk if you were so inclined, although my double is the settee on my cat as I have way less space than you.

The aft stateroom would be better at anchor, but it is a tri…touche’.

Also, you could add another BH in the middle if needed; the end of the galley and the end of the storage/edge of settee could make another BH midships easily which lay allow for some other subtle moves.

Also, the bunks look really narrow; add an angle and that is no bueno.

 

A lot to reply to, I'll try to keep it orderly.

The fore stateroom has a double bunk; it's roughly a queen mattress with a shitty taper ("cuddling space"). The two bunks in the mid-cabin are straight along their inboard sides and only curve along the hull; they're a little more than two and a half feet wide at the narrowest, making them roughly xl-twin mattresses. All of the bunks are set low enough for seating but the height of the hull (especially under the exterior standing deck) doesn't quite allow for "bunk bed" arrangement. They're adequate for individual seating. I wouldn't say I need more seating than this (what surface of a boat isn't a seat?) but it would track to integrate it into the radio room/chart table. I'll try to massage a convertible bed into that situation, for four permanent sleeping arrangements and 1/2 variable/convertible.

I've divided the mid-cabin quarters down the middle by placing storage on either side of them, closing in one end of each bunk and making a "hallway" through the middle (convoluted description, pic to follow). I've also integrated a false bulkhead midship to divide the galley and head from crew quarters; the structural bulkhead placement is pretty concrete as they placed based on LCF and mast placement.

No pic yet; life going on.

 

On berth headroom, I have been told by someone who knows, that you need enough headroom over a berth to allow a tall person to sit without banging her dead, on top of a rotund person who is lying down on the berth. Few small boats have that sort of headroom. Something to think about anyway.