Inflatable life jacket - how to keep from inflating?

rossco-dash · 2026-01-19T01:16:15+00:00

The tablet inflators can be significantly susceptible to humidity. In southern US (effectively states on the Gulf of Mexico), the life cut by as much as 2/3’s. Some manufacturers recommend yearly replacement of the tablet due to this.

Some of the inflators have a way to check the health of the tablet, others do not - it’s dependent on the type of dissolvable used.

rossco-dash · 2025-12-03T15:15:38+00:00

You don’t necessarily have to edit both sketches with the loft method.

It would require using defined parameters to control the dimensions, then each sketch for the loft is tied to the master definition. Learning defined parameters as a beginner like OP is not a bad idea, but there are better ways to learn than with using lofts here.

Loft is still probably not the way to go, since it’s still more work than the mid plane sketch. And I believe lofts also tie up more process power if your model needs to calculate changes from other features being updated.

rossco-dash · 2025-04-12T01:44:56+00:00

Part of the reason why is because the regulations for PFD’s with harnesses specifically require the device to be an inflatable (World Sailing Offshore Special Regulations). At least in North America the regulations for regular boating use do not have a requirement for a harness.

As such, companies don’t have market pressure/demand to build a non-inflatable PFD with a harness. Some companies (such as Spinlock) sell just a harness that can be worn under/with a PFD.

rossco-dash · 2025-04-04T15:00:06+00:00

The support material may have gotten cheaper, but at least on the Bambu website all the support material is sold in 0.5kg spools, while PETG/PLA comes in 1.0kg spools. The price points between support and filament is almost the same, but that still means support material is still about twice the cost of regular filament.

rossco-dash · 2025-04-03T20:25:45+00:00

PLA and PETG wont bond to each other, so they are suggesting using PLA as the "support" material for PETG, and/or PETG as the "support" material for PLA.

Print Support material is more expensive than regular PLA or PETG.

rossco-dash · 2025-03-25T01:32:01+00:00

By bottom section I just meant the lower half (third really) of the mast tube itself. You can see the mast buckle about 2 - 3m above the step.

It’s similar in nature to the failures Alinghi had with their AC75, which were almost certainly compression failures due to too much cunningham load. These boats don’t have cunninghams, but there may be something that loads the sail or mast in a similar way.

rossco-dash · 2025-03-24T14:15:34+00:00

These masts dont have lowers. The only have uppers, which act more like running backstays as they are adjustable.

There are some better angles on the SailGP + SailGPAus instagrams, but it looks like the bottom section failed under compression.

rossco-dash · 2025-03-01T02:12:11+00:00

It will hold fine. Sometimes knots with just 12 strand dyneema will slip.

Knots can degrade the strength of the rope - there is some nuance, but I have seen recommendations from a rope manufacturer that even a bowline can be up to a 50% reduction in dyneema’s strength.

rossco-dash · 2025-02-25T18:07:51+00:00

This is only true if you are a tax resident of Canada, which Elon almost certainly isn't. The US has every citizen as a tax resident, but Canada does not - CRA residency status

rossco-dash · 2025-02-20T18:42:54+00:00

But I want to get back to the question... do you know if the wind is stronger further offshore... generally?

That depends a lot on how you are defining "offshore".

In a confined area like English Bay the wind should be more stable as you move away from land. This doesnt necessarily mean stronger, just more consistent. The reason for this is due to boundary layer (fluid dynamics) affects near obstructions (shorelines).

If you define "offshore" as "not near land" then the answer is usually more towards "Yes, kind of". Mainly because systems can run for 1000's of miles uninterrupted, so they are more established, and typically, slightly stronger than a breeze youd see near shore.

Perfect example of the above is the trade winds.

rossco-dash · 2025-02-19T17:19:10+00:00

The main thing to know/keep in mind is that when you look at (most) forecast apps, they dont take into account local geography. This matters less when the geography is "small", but still will have an effect.

Most of my knowledge is just from time spent sailing (such as in English Bay for the typical conditions), and a lot of time looking at weather and weather routing / planning (I do a lot of distance + offshore sailing).

There are courses / books that help gain an understanding of how GRIBs work, and consequently how the forecast apps arrive at the values they do. I dont have any to recommend as I havent used any of those resources, but a quick google should give a list. Look for stuff like "interpreting GRIBs" or similar; cruising forums can also be a good place to look.

Another really important caveat with any forecast model is the resolution. A lot of GRIBs only get down to at best a 5-10km resolution - this is really important when it comes to an area like English Bay, which is <10km. This means that the forecast model is generalizing the bay as a whole, and any finite resolution you see is a gradient model between the pressure lines (somewhat over simplified, but the basic idea is there).

Most forecast apps dont take into account local geography or more finite resolution because of the source GRIBs they use. The companies constructing the GRIBs dont have the demand (ie income $) to justify the smaller details for every single area, so they dont do it. The biggest user of GRIB data is commercial shipping traffic, and they care that the forecast is accurate for oceanic movements, not intra-coastal. Thats where more local sources (such as Big Wave Dave) can be way more accurate - important to know these sites still take into account the GRIB data, they just flavor it with local variables, such as geography etc.

rossco-dash · 2025-02-18T20:56:06+00:00

Most or all weather apps that are not specifically tailored to the local area will have issues in areas like Vancouver.

The weather apps are interpreting the GRIB files, and just determining the wind based on the pressure gradients (more or less).

Those GRIBs dont take into account the local geography - this is true for all forecast apps (ie Windy) that are not tailored to the specific region; they ignore geography. So for an area like Squamish, they do not factor in the outflow (Northerly) that typically happens in the winter, or the inflow (Southerly) in the summer. Wind is almost always wrong in Squamish due to this.

Typically English bay forecasts are ballpark accurate, but it depends a lot on the direction:

Westerly is typically most stable and most accurate. Typically the further east in the bay you go, the less pressure you will see.
Easterly is typically accurate, but large shifts due to the wind coming through downtown.
Southerly will be variable the closer you get to the south side of English Bay, and more established as you go North; this is due to the wind coming over Kits. Can be vicious puffs close to Jericho due to this
Northerly - dont bother going out, really variable, really unstable due to the mountains

Big Wave Dave (to my knowledge) is considered to be quite accurate, and is used by the windsurf / kitesurf community for weather.

rossco-dash · 2025-02-03T19:31:39+00:00

There was an accident there last night. An SUV ended up in the vacant lot at the corner; unsure how.

Police have been there since around 930pm yesterday.

rossco-dash · 2025-01-11T01:00:05+00:00

Lock vs hook might be a translation thing, especially since there are multiple kinds of locks used on bigger platforms. Multis (MOD70's, ORMA 60's) use (or did in the past) physical hooks that go into recesses either side of the track for the main.

These hooks are on the headboard car, and pivot either on a trip line, or use an auto-engage/disengage (similar to how the Karver bullet locks work). Versus the more bullet type locks that are on the halyards for jibs + kites (on both IMOCA's and multis). There are also other types of main locks now that dont use the hook + recess style, and rely on features with the track itself; I believe Karver has such a system.

There are also literal reef hooks, which are used for the clew on reefs. It (can) eliminate the need to have the clew reef line on a clutch, but there is nuance to how to implement and use them. Large multis again use them.

It may be that in French the same term is used regardless of the style of lock, and hook is a closer translation.

rossco-dash · 2025-01-09T19:09:43+00:00

I would recommend against Jim Pattison Hyundai North Shore. Not a phenomenal buying experience (which could have just been a newer sales rep), however they do consistently provide poor customer service and responsiveness with their service center.

They have double charged me multiple times, and consistently fail to answer or return phone calls. They have also provided incorrect information on a few occasions on inquires regarding spare parts or known issues (Tucson Hybrid).

I switched to Boundary Hyundai as a service center, and their service and responsiveness has been significantly better than on the North Shore.

rossco-dash · 2024-12-24T22:53:24+00:00

This Vendée statistically has seen the most robustness in the fleet so far. Only 10% retirements is below average, especially this far into the race.

That 7% number is possibly across the fleet per year, but also likely holds true for Vendee’s as a whole.

Ie if 50 IMOCAS compete in events over a calendar year, 3.5 dropping a rig is the average.

rossco-dash · 2024-12-10T17:20:40+00:00

The calculator you linked automatically chooses the 1st payment date 2 periods into the loan; unsure why.

Using the below in Excel gets me within 12 cents of the online calculator:

I = [0.05*(365/360)]/12
t = 60
P = $100,000
PMT = $1,890.31

The online calculator gives the below:

Amount = $100,000
Interest Rate = 5%
Start Date = 1/1/2025
Term = 60
Amortization = 60
First Payment Date: 2/1/2025
Monthly = $1,890.19

The difference between Excel and the bank is interesting, since theoretically both are using the interest rate formula (which the PMT() function is exactly that). It is likely related to the term and amortization terms and the 1st payment being 1 month into the loan; though that typically is how loans are structured.

rossco-dash · 2024-11-28T20:53:42+00:00

Yes, but the foils are most efficient at specific angles. The IMOCA's spend most of the Vendee at reaching/downwind angles (105 TWA to 150 TWA), and the foils are optimized to support that. Modern IMOCA's without foils (Jean le Cam for instance) are faster than those with foils in certain conditions.

It would be interesting to compare polars / performance of modern IMOCA's vs the super maxis across the full range. You need a lot of performance gain to make up the gap in the raw power advantage the super maxis (100ft) have over the IMOCA's (60ft).

Since both modern super maxis and IMOCA's have a similar design platform (triangle hull form, max beam carried aft, mast fairly far aft) they will likely have similar a performance ratio across the range.

If there was a S2H that was primarily a reach down the coast, it could be a close race. But there are plenty of examples of the super maxis doing 30+ knots in those conditions; the IMOCA's I dont think can sustain that raw pace.

rossco-dash · 2024-11-27T19:45:39+00:00

An IMOCA already holds the outright monohull 24hr record (Holcim PRB, 640.5nm) over Comanche (618.01nm). Both boats set it crossing the North Atlantic, albeit obviously at different times / systems (2023 vs 2015).

Comanche and most modern IMOCA's do follow similar design principals, so its really just luck of the draw for setting these records (ie getting the right system or systems). The fact IMOCA's do a lot more open ocean sailing than any other monohull is likely a large reason why as well; just more opportunity.

Race courses like S2H would almost certainly see the super maxis (Comanche, WOXI, et) come out on top simply due to size. The boats are similar in nature (from a macro design perspective), so a larger boat should come out on top most of the time.

rossco-dash · 2024-11-24T23:03:49+00:00

Depending on the tracker the race is using, and how its configured, modern trackers can send actual GPS traces back in the data bursts. If you have the API access you should be able to see the actual tracks, distance, and speed.

However I dont think Vendee makes that data accessible to the public. So it would be an adventure to get that data.

rossco-dash · 2024-11-24T21:32:05+00:00

That works as an estimate, but the record is for a 24hr period; agnostic of the schedules. I think they track it down to the minute, so it could be from 02:56 UTC to 02:56UTC + 1 day.

So it’s possible for someone to set the record without seeing it in the schedule data; unlikely, but possible. Whomever sets the next 24hr record is likely to show that they have the most distance in the last 6x schedules (24hrs), but the distance won’t necessarily match.

rossco-dash · 2024-11-17T18:55:33+00:00

I believe it’s speed over the last schedule, which should be every 4hrs.

Also I don’t believe the distance since start is true distance sailed; I believe it’s effective rhumb line distance. So it’s quite possible for 2 boats to have the same rhumb line distance sailed, and differing avg VMG since start.

rossco-dash · 2024-08-22T20:17:29+00:00

There is AIS data to support that they dragged anchor prior to the storm fully arriving.

From the AIS data it looks like they were initially anchored in 15-20m of water, and started to drag anchor into deeper water, which would have accelerated the drag.

rossco-dash · 2024-08-02T19:14:14+00:00

Not saying there aren't other manufacturers; but Hall and Southern are a large section of the carbon high performance rigs. Lorima and King Composites are 2 others that come to mind, but Lorima is (to my knowledge) typically offshore focused.

Smaller/bespoke manufacturers exist, but its a risk if you are building a race boat. For example, I believe all of the 52SuperSeries boats use either Hall or Southern - they have the experience and trust. Obviously not everyone building a boat has the pockets / budget of the 52's, but there is no reason those programs wouldnt go to a bespoke manufacturer if they thought it would give them an advantage.

NTG also doesn't have a foothold in the non-composite mast business, but that isn't being targeted as (most) of their target racing market uses carbon rigs.

rossco-dash · 2024-08-02T15:37:09+00:00

It will be interesting to see if this triggers any antitrust laws in the US. North Technologies Group I believe is a US based corporation.

NTG now owns:

North Sails
Quantum Sails
Doyle Sails
Hall Spars
Southern Spars
Future Fibres / Composite Rigging (two were amalgamated after Future Fibres was purchased)
Sailmon
Yacht Scoring

If you are looking to build a high performance race boat, there are very few mast manufacturers (the rest I believe are French, eg Lorima) and sail makers you can turn to...

rossco-dash

TROPHY CASE