I think the first major take away I have from reading this thread is that I need to resist the "Multiples Of 100" as a forced rule.
It was never "a rule" (per se), but it has always been a
Default Assumption in almost every version of Traveller published. It even extends down into small craft, such that all small craft "have to be" Multiples Of 10 in their tonnages.
Every single design sequence in CT adhered to these "rules" for design (LBB2, LBB S4, LBB S7, LBB S9, LBB A1, LBB A4, LBB A8, LBB A10, CT AM1-8, etc.). It simply became Accepted Conventional Wisdom™ that all displacement tonnages come in Multiples Of 10 (small craft) or 100 (big craft).
In fact, one of the precious few designs to break with this pattern is (of all things) the Colonial Cruiser (LBB S9, p19) ... weighing in at 1250 tons ... instead of the 1200 tons published in LBB A1.
That ... precedent ... of everything is Multiples Of 10 or 100 then got ingrained into both Players and Referees (and thus into those of us playing Naval Architects) to the point that anything which deviates from that pattern of practice feels WRONG somehow. It feels unnatural. It feels ... perverse ... unclean ... radical, potentially even stupid and/or foolish.
My sense is that it's largely a function of how jump fuel gets calculated.
As soon as you stop working with Multiples Of 100 ... you start getting fractions of a ton in your jump fuel calculations. That then feels "messy" and you wind up with fractional tonnage "leftovers" that are a bit challenging to find a useful purpose for. The smallest discrete unit of something you can install into a design is 0.5 tons for a low berth, after all ... so any 0.49 tons or less remainders feel like wasted space.
LBB A5 came along later and codified collapsible fuel tanks, which can make use of less than 0.5 tons fractional remainders.
CT Beltstrike codified life support reserves consumables, which can make use of less than 0.5 tons fractional remainders.
But until you had those design elements, any tonnage fraction remainder below 0.5 tons was simply Waste Space ... which in turn would be rapidly assumed to be an "insufficiently optimized design" because the waste space existed. You could always throw that leftover fraction of a ton into the integral main fuel tanks (so it would at least be improving endurance), but even then it still felt like you were wasting space/capacity/construction costs/etc. with your design.
So everyone got into the habit of using
Multiples Of 10 or 100 every time ... because that's what the published designs did.
LBB2 was perhaps the most at fault for this phenomenon, because of how the "drive performance table" got constructed and RAW dictated how it was supposed to be used. A 200 ton hull used the 200 line to determine performance, but any hulls in the 201-400 ton range would use the 400 ton line to determine performance. So using any of the "intermediate" tonnages was SEVERELY penalized. This created a "don't color outside the lines" feeling to the way the design rules worked for hull sizes and drive performance in a variety of form factors. This is why the design sequence for the
Gazelle-class is so self-contradictory ... because under LBB2 it "has to be" a 400 ton starship, but under LBB5 it can be a 300 ton starship (which LBB2 would penalize).
There's also the fact that weapon hardpoint counts are tied to multiples of 100 (drop fractions in big craft, minimum 1 for small craft) helping to "enforce" the notion that big craft only get built in multiples of 100, because those are the breakpoints for being able to add hardpoints to hulls.
The
Multiples of 10 or 100 "rule" isn't necessarily
A Bad Thing™ per se, since it upholds the
Keep It Simple Stupid (KISS) principle. It does make a lot of the design sequence ... simpler ... and helps prevent the math from getting "too complicated, too quickly" for various aspects of the design sequence. So in that respect, it makes for decent Training Wheels as a precedent for how people ought to think about design sequencing of small craft and big craft. However, when that mindset hardens into concrete and stops being a Best Practices For Newbs™ and instead turns into THE ONLY WAY THINGS ARE DONE is when you pull out the straight jacket and foot binding in order to CONFORM to the ossified Conventional Wisdom™ which has outlived its usefulness.
Breaking away from the Multiples of 10 or 100 "habit" is not easy ... and it requires motivation to do so. That motivation can ONLY come from mathematical results in the design process which point to those "intermediate" tonnages being advantageous (somehow), which means you need to have a reason other than hardpoints for why you would want to do it.
LBB2 put enough "guardrails" around the intermediate tonnages in the RAW that even reaching for them was quickly dissuaded by min/max gamer mentality. It's only when you can "break out of the table" used by LBB2 and reach for the formula(s) that generated the LBB2 drive performance table in order to determine the performance of intermediate tonnages that a whole new range of possibilities (and opportunities) opens up.
In that respect, my house rules for
LBB2.81 Drive Performance Formula plus External Load Towing Capacity rules for starships is the "best" motivation around for choosing intermediate tonnages that do not follow the Multiples of 10 or 100 pattern, because of how the drive performance code parameters compute when you're using formulas (to get at the REAL answers) rather than a table (that shows you only minority fraction of the answers). It opens up the starship design space in ways that are internally consistent with CT, while still "breaking the mold" that has hardened into such brittle rigidity since 1977 regarding HOW (and WHY) things are done the way they've always been done.
Be open to various alternative numbers.
The trick is to find REASONS to choose alternative numbers.
Don't just do alternative numbers for "no reason" ... there has to be something in the design sequence that gets optimized by the use of alternative numbers.
For example.
If you're limited to TL=12 (so model/6 computer is available) and you want to use LBB2.81 drives to make the smallest possible J6 starship as an XBoat replacement and it needs to be 100-199 tons (so it can be single person crew) ... what are your options?
- Drive-E is code: 1 @ 1000 tons ... but is code: 6 @ 166 tons.
- Drive-F is code: 1 @ 1200 tons ... but is code: 6 @ 200 tons.
If you can make everything fit into 166 tons, you can "get away with" using a Jump-E drive in order to achieve J6.
If you can't make everything fit into 166 tons, you'll have to bump up to a Jump-F drive in order to achieve J6 ... but you'll still want to stay under 200 tons for reasons of crew manning (only needs 1 pilot). If you can make everything fit into 180 tons, use that as your hull form factor ... it just really depends on how everything "adds up" because there are a large number of items that "cannot be compressed" when working at these displacements (such as bridge, computer and stateroom accommodations).
I know how interesting I found some of the 150 dton scouts, but I admit, I tend to always try and force my ideas into an even 100 dton number.
As soon as you "reject the table in favor of formulas" all kinds of interesting things start happening in the 100-199 ton displacement regime while retaining the use of LBB2.81 letter drives. Power Plants become your primary "tonnage expense" because of the 10Pn fuel requirement, which really HURTS in such small form factors when you're trying to have leftover revenue tonnage. It makes for quite the interesting engineering design challenge to balance all of the competing priorities (displacement within the hull, construction cost, revenue potential when in service, etc.). Being able to successfully balance all of those competing priorities in a way that yields a superior product for a variety of use cases feels extremely satisfying (see: build a better mousetrap).
