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-   -   How to find a rudder design? (https://www.sailnet.com/forums/sailnet-faq/329416-how-find-rudder-design.html)

Capt Len 04-27-2019 11:54 PM

Re: How to find a rudder design?
 
If it's anything like Canadian rules and regs, Overnight guests are passengers requiring things like watertight bulkheads ,all sorts of fire alarms and gear ,just for starters.even if the boat never leaves a dock. Dept of Transport doesn't hand out the ticket easily Getting legal may be more work than getting the boat to sea. I was licensed for 18 day passengers and 6 overnight so got good at jumping hoops.building the boat was easier.

boatpoker 04-28-2019 12:02 AM

Re: How to find a rudder design?
 
Quote:

Originally Posted by Capt Len (Post 2051598808)
If it's anything like Canadian rules and regs, Overnight guests are passengers requiring things like watertight bulkheads ,all sorts of fire alarms and gear ,just for starters.even if the boat never leaves a dock. Dept of Transport doesn't hand out the ticket easily Getting legal may be more work than getting the boat to sea. I was licensed for 18 day passengers and 6 overnight so got good at jumping hoops.building the boat was easier.

I don't know about US rules but that's not the case in Canada. A friend has been running a B&B on a boat in Toronto harbour for 7 or 8 yrs. without having to follow TC passenger carrying rules as he never leaves the dock with passengers. I did his survey and have worked with TC on several Toronto tour boats approvals.

makobuilders 04-28-2019 04:09 AM

Re: How to find a rudder design?
 
Tall Ship, since your goal is having a vessel for sailing and chartering, and your goal does not seem to be restoration of a historic vessel, then have your naval architect design the new rudder in steel. Nice NACA airfoil shape. Semi balanced if necessary. It will be many times more effective than a wood rudder.

hellosailor 04-28-2019 02:37 PM

Re: How to find a rudder design?
 
tallsip, if you aren't lucky with dice and don't want to totally bodge the job (at a high price) then try to contact the builder or designed and find out what the rudder had been designed as. Otherwise spend the money on a naval architect or designer. It will be cheaper than getting it wrong--which is VERY easy--and then having to redo the job multiple times until you can it right.

Similarly on the prop. If you can't figure out what the transmission is, get a mechanic who can figure it out. You will need to know the engine, the transmission, and the weight of the vessel before a prop shop can even guess at what you need, and even then it may not be right on the first try. The same mechanic or prop shop can probably tell you what kind of shaft you need, and whether that also needs a shaft log and support, and just how long it should be to keep the prop clear of the hull and rudder.

"Close" is good enough for horseshoes, but you will find it often is simply an expensive mistake on something like a 100' long ship. Things come back to bite you, if they aren't right the first time. And finding good help is not easy--at any price.

makobuilders 04-29-2019 01:35 AM

Re: How to find a rudder design?
 
Quote:

Originally Posted by Tall ship surprise (Post 2051598602)
It would Portland Oregon. I'm hoping to get the big lady ready to sail down the west coast and set up down in Chula Vista CA this winter as a Air Bnb.
If I were more experience, I wish I could go around the world, and end up in maine. maybe catch lobster off the boat

I might get crucified for saying this, but here' a suggestion for your AirBnB...

If your engine/shaft/prop works are exorbitant (likely) then how about just pull the engine out and sell it for a couple grand. Plug the holes in the hull, fair the deadwood, install the high lift steel rudder that your naval architect will easily design... and go engineless.

It's a floating hotel that doesn't move. If you want to go for a sail then take your two launches and use them as tugs to tow out of the marina into open water. Then sails up!

Might make some good marketing points on the brochure as well.

MarkofSeaLife 05-09-2019 02:40 AM

Re: How to find a rudder design?
 
I spose it's all to late as the OP hasn't been back and said he was buying this 100ft ferrocement "tall ship".

But I chuck my warning in that the rules change when the boat is over 24 Meters/80 feet internationally.

I don't know about the USA but I feel they would be in compliance with it.

A private person can't captain a boat 24 metres and over unless they have a pretty good license.
To employ a skipper to do it the boat would need to be seaworthy.
For it to be used as a commercial enterprise the USCG would want it inspected, even as a 'dockside attraction' or whatever BS word they used for the Bounty.

As most ferrocement boats are home built (probably in the 1970s) no naval architect will look at designing a new rudder, or if he wanted to, could.
One wonders how the old rudder disappeared, along with the prop and shaft, except for some weird misadventure.

The word 'misadventure' rings clear in my mind... of this boats past and its future.

Finally I think everyone here has written very politely in response to this guy's endeavour.
I hope he has reconsidered buying this huge boat and perhaps jump a bus to safety :)


Mark

makobuilders 05-09-2019 03:55 AM

Re: How to find a rudder design?
 
Yes the OP seemed to have disappeared and I'd be curious to know how he is progressing, or what his final decision is.

BTW, if I recall correctly, that 23.8 length barrier is measured as the load line length, similar to length between perpendiculars. A creative naval architect could conceivable measurement and document the boat's LLL as 78ft even thought the overall is 100ft.


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