How to (not) break a mast.

[GordMay]

Originally Posted by DougR

I'm in the camp that says your mast bend is not excessive......

Attached is a page from the Selden Mast tuning guide* that deals with mast pre bend. In the event that its not legible, the takeaway is that they state that "the mast should not be straight, it should have a certain amount of prebend. 0.5% of the fore triangle height is normal for a starting position, and 2% of fore triangle height should not be exceeded.
Of course, all the rigging should be in place prior to approaching the limits.

If you have a 19.5 meter mast, the minimum recommended prebend is about 10cm.

Some interesting & informative reading, on mast bend:

The Explanation of Mast Bend” ~ by Ullman Sails

”There are 4 different types of bend we look for in setting up a mast.
Mast Rake, Pre-Bend, Max Bend, & ide Bend or Sag ...”

➥ https://puertovallarta.ullmansails.c...ion-mast-bend/



“What You Need to Know About Rig Tune & Performance” ~ by Dave Flynn. Of Quantum Sails

”... To master the rig, there are four elements you need to understand: rake, athwartship tuning, mast bend, and headstay sag. Each of the four elements of rig tune either adds power or takes it away. If you understand the basic mechanics of each element, you can tune your rig to improve trim and overall setup ...”

➥ https://www.quantumsails.com/en/reso...ne-performance




See also
* “2.2 Mast deflection curves”, in Selden’s [mast maker] ‘Sailmaker’s guide’

”... Our spars and fittings are designed to cope with a maximum longitudinal deflection of 2% of the fore-triangle height (FH). On fractional rigs the maximum deflection can be taken as being 2% of the mainsail luff (P). These values are guiding principles only ...”

➥ https://support.seldenmast.com/files.../595-542-E.pdf



and

“8.1 – Tuning Your Rig” ~ by UK Sailmakers

”... The first job is to set the rake of the mast. If you are putting the mast in the boat for the first time, set the mast so that it leans back a few inches. More rake adds weather helm...
... Now you can tackle fore-and-aft tune. Tighten the backstay to the maximum tension you will use while racing. At this point you should have the maximum amount of mast bend for your boat. If you don’t have enough bend you can ease the headstay or move the mast either forward at the partners or aft at the step. (To check fore-and-aft bend, attach the main halyard to the gooseneck and pull it tight. Mast bend is the maximum distance between the halyard and the mast. See diagram) ...”

➥ https://www.uksailmakers.com/encyclo...ning-your-rig/

[Ixium]

Originally Posted by Peter Hunt

On a different note, you can (probably) see a live stream of me crossing the Altantic here, it is up whenever my Starlink is up.


Its not great quality, and super boring, which is what I look for in a crossing, but kind of cool. Couldn't do that a few years ago.


The link looks sketchy, but is simply an rtsp video stream forwarding site. I didn't pay for a nice link, it's free.


I am running, with my spinnaker pole tied to the mast base (they could not install my spinnaker pole rail for some reason, par for the course)


Nothing is perfect, but it is working!


PHOENIX REBORN LIVE ATLANTIC CROSSING
https://rtsp.me/embed/h8yb25NQ/

What camera are you using and do you leave it up for storms? Has it performed as you thought?

I want to put one on my front mast of a cat-rigged boat in order to see where to go in shallow waters when the time comes. Live feeds would just be an extra fun bonus.

[Peter Hunt]

Originally Posted by Ixium

What camera are you using and do you leave it up for storms? Has it performed as you thought?

I want to put one on my front mast of a cat-rigged boat in order to see where to go in shallow waters when the time comes. Live feeds would just be an extra fun bonus.

You honestly can use about any Camera that outputs 1080ish... I prefer less for the stream, 1080 for seeing things. I am using a Wyzee camera, v2 which is not waterproof or meant to be outside, it was a project I came up with on the many days of nothing that a crossing provides.


I will likely get a cheap waterproof camera to replace it. It has made it through light rain, and no splashing that I can tell.


The hard part is streaming, I might start another thread on what I have learned. Particularly form Starlink, which has its own challenges due to Carrier Grade NAT. (No incoming connections)

[Schapera]

I note your reference to Morgans Cloud website and tuning instructions. I have used them for years and find everything the recommend to be FAULTLESS, which is why I remain a subscriber. I have a 45ft yacht with similar mast and had similar bend issues so totally understand your concern.

[Scubaseas]

Originally Posted by s/v Jedi

I recommend you buy this book: https://www.amazon.com/Illustrated-S.../dp/B07F3RXWSR

This is a Kindle download so available instantly. It shows exactly how to tune your rig.

Another vote for this book. Very well illustrated.

[nofacey]

Mast bend as shown fine.

Having Mast bend is totally normal, stabilizes the mast, and is usually built into your mainsail to boot.

Mast rake should be specified by the original naval architect - then gets adjusted by how the boat handles in strong winds. If you have excessive weather helm, decrease rake.

You’ve mentioned some pretty disturbing issues with the mast step and partner. I’d get my ass to a decent yard, find a trustworthy rigger, haul the rig, and get those fundamentals fixed before worrying about any other rigging details beyond keeping it up long enough to get there.

Not 100% sure where you’re headed…..Peake’s or Boatworks in Trinidad would be my first choice for capability & cost.

[Pete7]

Originally Posted by s/v Jedi

I recommend you buy this book: https://www.amazon.com/Illustrated-S.../dp/B07F3RXWSR

I recommend reading this book. However, sadly despite being sat on a table next to me, I haven't started it yet.