NavList:

First, in strictly human terms. We are grateful for their safety and safe return.  Nothing in any remarks detract from that precious fact, nor do I have anything other than a visual and scanty reporting. 

In my sailing years, the engine was strictly a secondary device. Ours was a cantankerous old diesel that didn't always like to participate fully in any adventure.

It has an upright rig and apparently sails in some sort of repair.   It wasn't motoring all the way to Tahiti, so we assume that at one time they were deemed functional.  Even if damaged, there is visually a enough there for an effective jury rig. That should be part of your bible when sailing to far off places.  Stuff happens. You should be able to use resourcefulness to cook up ways to at least go under own sail power even if primary rig is damaged. Spare sails anyone...several different jibs are so common on sloops as to be like changing underwear...no 1, no2, genoa...etc. Roller furling nowadays makes that in some eyes not necessary...not in mine..I want some spares....including small sails designed to maintain stability in a blow.

It would appear that there was a significant loss of direction finding.   Primary GPS lost when engine went?  I can guess and insinuate...used battery power till no charge...   If I lost engine power in ocean travel, and had no backup GPS,  I would disconnect everything but the battery from that and turn it on a couple times a day to check my plotted travel....A ships battery on that use ...many months (and save the reserve for lights if a ship is seen).  Problem is...you don't think if you haven't been burned before..and perhaps you crank and crank the engine until the batteries are dead praying that one more turn of the key will be your miracle....  foolish..perhaps..but very very human...how about...a solar panel... pretty bulletproof backup...  .

Good thinking..they had a way to make water...with four lives at stake...that saved them most likely.....gathering rainwater with sails in some parts of the world...but that takes creativity and storage, etc...

Navigation...most of us are probably pretty sure that emergency navigation was not a strong suit...  If you are doing that trip..you have lots of possible landfalls in the islands...  Thor Hyerdahl left South America and made Polynesia with an essentially downwind vessel...a raft .......A sloop, even if crippled to a jury rig, is likely to be able to follow a similar course.   They did have a sextant and navigation skills on Kon Tiki....which helped with course trimming........

Find direction with stars yes, but...if you didn't take references with you.... declination and rising and setting times are not in most brains...using stars for latitude requires knowledge we can guess they did not have....  Most navigators, sailing downwind, using latitude line navigation from good star data if no sextant...should make landfall....  of course if you have no charts...or undetailed charts...that part of the world is scary when you get near land....  coral is a hull killer...

 A good magnetic compass I hope was on board, that helps..Of course if you not only lack sky tools, but charts and ocean data,  you may have no idea how the main ocean currents are carrying you along..over weeks or months...big error...also of course wind leeway etc... etc....  Lack of dead reckoning skills and accurate data is deadly here. One good blow can really much you up too...

We can specualte on and on....and suggest back and forth what should or shouldn't be the alternate plan..(I barely scratched it.)....but...We thus suppose that limited skills, perhaps physical limitation (strength, etc) may have limited the ability to adapt to what was encountered.   I would guess that a skilled ocean sailor would have handled that in stride without much ado, both with prior planning, equipment, and skills.

Just an EPIRB and other satellite long range communication sure would help folks if all else fails...

Basically, there is no substitute for planning, learning, and practicing skills. 

That said, more than once at sea I have had some event or other that was totally unplanned..and learned from the experience.

At least it has a happy ending, thank god all survived safe, and it may lead others to plan carefully or pause......

Of course the way the story is written will leave a lot of uninitiated folks the idea that sailboats are helpless without engines...which is almost too funny.....

MC