Reviewing the Davis MK15 Sextant
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- Опубликовано: 17 апр 2023
- People often ask me what sextant I recommend they buy to begin learning celestial navigation. Now that I've had more than a year with the Davis Mark 15, I decided I should give a detailed review explaining why I think it fits that purpose.
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Thanks for watching, those of you who showed up for the Premier.
Great video.
I have one of those...somewhere in the basement...I think it was a Mark 15.
Been so long.
Bloody GPS!
If it has the split half horizon mirror, its the 15. The 25 has a beam converger with a full width translucent horizon mirror. My C.Plath has the half mirror, so more like the 15. I suspect I wouldn't have liked the 25 nearly as much, even if it is supposed to be 'better'.
@@protothad837 Yes it was the split mirror.
For the record I also have the Mark 3, it was my first sextant and even though you call it a toy, that and a couple books got me started.
I think I purchased it for $35, the artificial horizon was something like $15.
The Mark 15 was a major upgrade to the Mark 3 but it served its purpose teaching me all the basic principles for cheap.
@@sissyfus6181 Thanks for the info on the 3. The descriptions I read of it say you can get within 10 nautical miles by taking multiple sights and averaging, so I can see it being useful as a backup or for the lifeboat ditch kit... so calling it a toy is probably unfair on my part.
@@protothad837 "... lifeboat ditch kit..."
Nowadays my ditch kit would have a VHF with AIS, a personal epirb and a Garmin with mapping and inReach.
The Mark 3 might be fun to pass the time and not rack up a huge messaging bill on the inReach.
;-)
@@sissyfus6181 Oh definitely... first line of defense is the best possible technology. But layered defense is a good idea... so I think I would always want that sextant as a backup.
Nice review. I'm more of a hobbyist, but have always been fascinated by celestial navigation. I bought a mk25 a while back and have taken a few 'noon sights' with it. Of course my skill level is still 'novice', but I've been able to 'fix' my location to within 8 miles of gps (so I'm rather proud that I'm learning that).
I have noticed as you point out the calibration issue. In fact, I've taken to measuring the index error before/ after sightings and found it shift slightly (although, some of that may be my aging eyesight).
Anyway, enjoy your videos and looking forward to seeing more.
I found a Mk25 dirt cheap in the classifieds. Couldn't resist. Doesn't look like it was ever used. Pretty nice features but the full horizon mirror would not be my first choice for star sights. I'll be doing a video shortly highlighting the differences between the 15 and the 25.
Yeah, I'm more a fan of a half mirror over a beam splitter exactly because I prefer doing star sights when I can. I look forward to seeing that video comparison. 👍
Thanks for the review. Was chasing one of these online through Facebook and it just fell through, which was disappointing. Got my eye on another and will hopefully be a student of so many of your videos soon! Really appreciate the time you take to do these and share your knowledge. Cheers.
That was a good review.
“You recorded all this in a pool!!!”
Just giving the flat earthers a voice :)
Thanks for another great video
Very cool
Flat Earthers be like, "What's that he's holding?"
Yeah, I've yet to see any evidence that any of them have touched one, let alone used one.
🤣🤣🤣
@@protothad837 some of them were even directly offered a free one, but declined
Instructions unclear. Where do I find a sex tent?
Ty for this video. I just didn't want to be scam online lol.
The $23 Harbor Freight decorative brass sextant does have sun filters (allegedly) but only 2x scope.
If it is decorative, I wouldn't trust that those filters have the correct amount of polarization. You need something pretty substantial when sighting directly at the sun.
I had a bad experience with DAVIS. I bought a new M15 sextant (on eBay) and the lens came loose from the 3X telescope. There was no way to fix it. I sent an email to Davis, including photos, and got no response. I sent it again and was told that customer service would respond. The answer came after I insisted, once again, and was "we don't have stock of this part. I asked for more information and no answer. They totally ignored me. So, a serious company is one that cares about the customer and this was not the Davis case with me.
Sorry to hear about your negative experience.
The objective lens is held in place by a plastic ring with a press-tight fit. If the ring is missing you should still be able to glue the lens into place.
Given that so few people nowadays buy a sextant I can understand that Davis might have parts issues.
Hi Thad,
were you asking about a lighthouse recently on Oakley's channel?
I might have said something in text comments a few weeks back, but I haven't been a guest on the live stream since the one hilarious occasion more than a year ago. The video I made responding to Tenth Man included some sextant sights taken near a lighthouse... so if they are talking about a lighthouse, maybe it relates to that?
Honestly, I haven't had much interaction with Oakley or his crew since he embargoed my videos and banned me from his server. Seems like I struck a nerve. 😎
@@protothad837 No, it's not that. In the comments section below FED 1903, someone quoted screenshots of a chat between Nathan and Anthony Riley where Nathan basically confirmed the globe. He didn't realise at the time that the chat was visible. A commenter by the name of Proto 34 asked about the lighthouse that was quoted. My comment explaining the chat was quickly deleted. A previous comment of mine where I told the guy that the chat could be found in one of my playlists was subsequently also deleted. 🤣
@@marcg1686 No, that was not me... just someone with a similar name it seems.
It's a beginner sexton , so if u can not handle it and put it in a box in your closet no big lost in money compare to a $ 1,000 sexton
Yes, that's a fair assessment. It's a good beginners' sextant to start learning on, or an inexpensive backup sextant in case GPS or your primary sextant fails... but I would still recommend investing in something a bit more rugged for serious ocean navigation.
Hi Thad, thanks for sharing. I fully concur. My biggest gripe with the Mk15 is the telescope. I use the sight tube when adjusting the horizon mirror. Another minor gripe is that the shades flop around a bit the more you use it. Other than that, it works just fine. Mine has an index error that varies between 7 to 9 minutes on the arc.
May I humbly suggest the following mod? It really does help.
ruclips.net/video/QKcMCC6XpJc/видео.html
Thanks... that's a really clever hack.
Where can I find a model which works on the flat earth?
Any sextant would work on a flat earth. That is not the problem. The problem is that there are no sight reduction tables for a flat earth. No coordinate system either. Since the flerfballs can't agree on whether the sky is something planar or dome shaped they can't define the geographic position of a celestial body.
@@marcg1686 At the most basic level, 60 nautical miles per degree doesn't work.
And it's downhill from there.
@@sissyfus6181 The 60nm per degree is not intrinsic to the sextant. The sextant merely measures an angle. The flerfballs have no way of deriving anything useful from that angle.
@@marcg1686 Yes, they hilariously think 60 nmi / degree somehow works on a right triangle when it is clearly an application of the arc length formula.
Thad, are your there?
Just hanging out watching the coronation with the British side of the family... What's up?
@@protothad837 I pulled the trigger on a C&P dating back to 1959. The micrometer drum doesn't have a Vernier scale, but doesn't trouble me. The handle has a screw cap for the batteries. Am I right in thinking that the batteries are installed with the +ve pole facing upward?
@@marcg1686 I honestly can't say since my C.Plath was missing both the light and manual when I bought it used 35 years ago. I just use a pen light if it is dark.
@@protothad837 Thanks. The +ve pole must face upwards. I tried with the batteries from the Astra, but to no avail. It doesn't really worry me. It really is nice though. I like the fact that I can leave the index arm and the shades set any way I please and it still fits into the case.
The plastic "Toy" sextant!
Pity the poor soul who finds himself adrift in mid ocean with only that "Toy" sextant to help him!
May God have mercy on his soul!
Well, as I point out in this video, the mark 15 does just fine, yielding results comparable to more expensive sextants... which is why it is popular as a backup and to learn on. I would still obviously choose my C.Plath over the Davis... but you can find plenty of serious sailors with the MK15 on their boat.
It's very much not a "toy". I've had one for a few years, and although maybe not as precise, or as elegant, as a high-cost metal sextant, it does give pretty accurate measurements. People have crossed oceans using the David Mk 15, so it's certainly not a toy.