Hobie Stability

I know the question of "how many people can you put on the boat" gets asked fairly regularly on this forum. Many of the more experienced sailors know exactly how their boat handles with different weights, skills, and conditions. They often offer very useful information and guidance to those who ask. I would like to offer a bit more insight into what to consider when deciding where to set the occupancy limits for your boat.

I couldn't find any information for the total volume of the hulls for the different cats. I ended up measuring the girth of the hulls from my boats at 2ft intervals and estimating rough volumes for the different hulls. At some point I may make some more accurate measurements.

H14 - ~8 cubic feet ~ 500 lbs. buoyancy per hull (in freshwater)
H18 - ~20 cubic feet ~ 1200 lbs. buoyancy per hull

With this information there are a few crew weight points/boundaries that might be useful to keep in mind.
- class rule minimum weight
- max flyable weight (crew + boat = single hull buoyancy)
- max recommended weight
- capsize weight (crew + 1/2 boat = single hull buoyancy) (crew on a hull, not hiked or on the trapeze)

For any crew weight below the 'max flyable weight', a hull would have to lift off the water for the boat to flip (not including pitchpoling). For crew weights above the 'capsize weight' it becomes possible to capsize the boat by being in the wrong place (without any help from the wind).

H14 example:
The generally recommended crew weight for an H14 is about 150 lbs. That plus the weight of the boat (around 240 lbs.) puts the total boat weight at 390 lbs. which is around 80% of a single hull's total buoyancy. It is possible to fly a hull up to a crew weight of about 250 lbs. (100% of single hull buoyancy). The max crew weight indicated in class rules is around 350 lbs. (590 lbs. total or 120% of single hull buoyancy). That is enough weight to sink a hull but if the boat is kept fairly balanced there should enough freeboard to compensate for gusts. The 'capsize weight' would be around 380 lbs. for the crew. I have sailed my H14 with about 400 lbs. of crew weight but I don't trust my skills with wind over 10mph at that weight.

About a month ago I tried taking my whole family on it (over 800lbs. including the boat) and it felt like trying to stay on top of a submerged beachball. I do not recommend that and we have since gotten an H18.

H18 example:
- Min crew weight = 295 lbs. (men), 260 lbs. (women) (about 60% of single hull buoyancy)
- Flyable up to 800 lbs. if all crew is sitting on the windward hull (100% hull buoyancy)
- Capsize weight above 1000 lbs. (116% hull buoyancy)
- No maximum crew weight indicated

My main takeaways are:
- For crew weight below the 'max flyable weight', the windward hull will lift out of the water and provide some more advanced warning before the boat flips (easier to deal with though still possible to flip).
- The leeward hull will tend to submerge for crew weights above the 'max flyable weight' up to the 'capsize weight'. But with some weight distribution management, it is possible to still have plenty of warning of a possible flip.
- For crew weights approaching and exceeding the 'capsize weight', skill with handling and weight management become more critical because smaller mistakes or variations can lead to a capsize.
It should be noted that if the crew is all on a wing, hiked out, or on the trapeze, the 'capsize weight' is reduced.

_________________
Sam

'84 Hobie 14 Turbo
'84 Hobie 18 Magnum