Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 18-12-2012, 17:03   #91
cruiser

Join Date: Feb 2011
Location: medusa NY
Boat: Tayana Surprise 45 schooner "Union Pacific"
Posts: 2,098
Re: Steel or Aluminum

Quote:
Originally Posted by nimblemotors View Post
So really, you have it figured out and don't need any input from CF.
To answer your OP question, use steel, you can hire cheap welders for it,
rather than Al, which requires highly skilled welding.
Be sure to put up a Blog and tell everyone how you got it done, how much it costs, and how long it takes, etc. We want to know.

yes, i will.
i am a professional photographer, and will be taking thousands of photos and a time lapse.
i plan to do a e-book after its all done as well.
and yes, i will be using steel.
__________________

__________________
scoobert is offline   Reply With Quote
Old 18-12-2012, 17:21   #92
Senior Cruiser
 
44'cruisingcat's Avatar

Cruisers Forum Supporter

Join Date: Sep 2006
Posts: 7,454
Images: 69
Re: Steel or Aluminum

Quote:
Originally Posted by scoobert View Post
That table says 100hp is equivalent to 42.5kW, which is about 57 hp, so not triple the power. Add in a bit of salesemanship, and you'll likely find one diesel horsepower is pretty much the same as an electric one.
__________________

__________________
44'cruisingcat is offline   Reply With Quote
Old 18-12-2012, 17:31   #93
cruiser

Join Date: Feb 2011
Location: medusa NY
Boat: Tayana Surprise 45 schooner "Union Pacific"
Posts: 2,098
Re: Steel or Aluminum

its not the first place i have read it.
many years ago i had a job that required me to drive 42 miles a day, i was going to make an electric car at that time, as they did not even have a mass produced car.
i soon learned that all i would need to replace a 250HP mill was an 80HP electric motor, and it would roast the tires from the car.
electric motors have boat loads(pun intended) of torque.

that is not the company i will be buying from.
i will be buying from an electric engine builder.
much cheaper. and liquid cooled.

i don't know anyone who goes full power either.
my boat has 200HP, besides getting onto plane, it rarely goes full throttle.
once on plane i can back it to 1/4 throttle.
now take a displacement design.
how many times do you go full throttle?
do you ever?

i believe the 2-3 times the power refers to diesel as 2 times, gasoline as 3 times.
__________________
scoobert is offline   Reply With Quote
Old 19-12-2012, 05:01   #94
Moderator
 
noelex 77's Avatar

Cruisers Forum Supporter

Join Date: Jul 2007
Location: Living on dirt waiting for our new yacht to be built.
Boat: Half built Bestevaer.
Posts: 10,619
Re: Steel or Aluminum

Scoobert I do admire your optimism and enthusiasm, but just for quick reality check. Lets suppose you manage you build your cat on time and on budget even then you will cruising on a vessel that by my rough calculations is:

5x bigger (by volume) than the average cruising boat
10-20X the battery bank of the average cruising boat
7-8X times the sized diesel engines than the average cruising boat + 2 electric engines.

What is cruising budget going to be?
Can you afford 5x the budget of the average cruising boat?
Have you the time for at least 5x the maintenance and repairs?
__________________
noelex 77 is offline   Reply With Quote
Old 19-12-2012, 05:33   #95
Registered User
 
transmitterdan's Avatar

Join Date: Oct 2011
Boat: Valiant 42
Posts: 4,025
Quote:
Originally Posted by scoobert View Post

its a common knowledge that an electric engine is 2-3 times the power of a diesel or gasoline.

how many times do you run your engines at full throttle? as in wide open?
well, that is your maximum power. for an electric engine maximum power is at 0 rpm. so i can run huge slow props at full power.
I have not followed this thread much since it borders on nutsville. But could not resist commenting on this whopper.

Power and torque are completely different units of measure. Any motor not turning is producing exactly zero power by definition. A locked rotor of an electric motor can generate torque but not power. Mechanical power produces motion by definition.

If you find yourself in force 8/9 winds near a lee shore you will push the throttle all the way forward. And most likely will wish for more thrust no matter how much or little you have. But in your case I am not too worried that will ever be an issue.

You may also want to look at a few propeller power vs. RPM curves before you get too far into the design.

Dan
__________________
transmitterdan is offline   Reply With Quote
Old 19-12-2012, 15:45   #96
cruiser

Join Date: Feb 2011
Location: medusa NY
Boat: Tayana Surprise 45 schooner "Union Pacific"
Posts: 2,098
Re: Steel or Aluminum

Quote:
Originally Posted by noelex 77 View Post
Scoobert I do admire your optimism and enthusiasm, but just for quick reality check. Lets suppose you manage you build your cat on time and on budget even then you will cruising on a vessel that by my rough calculations is:

5x bigger (by volume) than the average cruising boat
10-20X the battery bank of the average cruising boat
7-8X times the sized diesel engines than the average cruising boat + 2 electric engines.

What is cruising budget going to be?
Can you afford 5x the budget of the average cruising boat?
Have you the time for at least 5x the maintenance and repairs?
The engines will be small and smaller. And rarely used.
I keep hearing about maintenance, i budget for 40 hours a week.
I have no idea what maintenance will be required on a new boat kept in mostly fresh water? But i believe i will have some.
Time will be limitless. I would like to keep two people on anchor for less then 1000 a month.
__________________
scoobert is offline   Reply With Quote
Old 19-12-2012, 15:53   #97
cruiser

Join Date: Feb 2011
Location: medusa NY
Boat: Tayana Surprise 45 schooner "Union Pacific"
Posts: 2,098
Re: Steel or Aluminum

Quote:
Originally Posted by transmitterdan View Post
I have not followed this thread much since it borders on nutsville. But could not resist commenting on this whopper.

Power and torque are completely different units of measure. Any motor not turning is producing exactly zero power by definition. A locked rotor of an electric motor can generate torque but not power. Mechanical power produces motion by definition.

If you find yourself in force 8/9 winds near a lee shore you will push the throttle all the way forward. And most likely will wish for more thrust no matter how much or little you have. But in your case I am not too worried that will ever be an issue.

You may also want to look at a few propeller power vs. RPM curves before you get too far into the design.

Dan
Its ok belief is not required, nor is percipatation.
You are 100% correct. An electric motor has maxium torque at 0 rpm and that does not calculate to hp rating. I am not here to give an engeneering class.

When the steel cat does run into rocks or whatever, it will take a lot of force to penetrate 1/4" steel.

Sent from my iPhone
__________________
scoobert is offline   Reply With Quote
Old 19-12-2012, 16:26   #98
Moderator
 
noelex 77's Avatar

Cruisers Forum Supporter

Join Date: Jul 2007
Location: Living on dirt waiting for our new yacht to be built.
Boat: Half built Bestevaer.
Posts: 10,619
Re: Steel or Aluminum

Quote:
Originally Posted by scoobert View Post
The engines will be small and smaller. And rarely used.
.
Your engine A at 40HP is about the average size for a typical cruising yacht. Your engine B is extra and at 300 HP is considerably larger.
Quote:
Originally Posted by scoobert View Post
I keep hearing about maintenance, i budget for 40 hours a week.
I have no idea what maintenance will be required on a new boat kept in mostly fresh water? But i believe i will have some.
Time will be limitless.
Even if you are correct 40Hrs is a full time job for one person.
Quote:
Originally Posted by scoobert View Post
I would like to keep two people on anchor for less then 1000 a month.
This is not realistic for a 65 foot catamaran.
Have a look at the cost of haul out, time on the hard, and anti fouling paint as an indication of just some the sort of costs you will be starting to encounter.

I am trying not to be negative, but it better to confront he realities now rather than later.
__________________
noelex 77 is offline   Reply With Quote
Old 19-12-2012, 17:13   #99
cruiser

Join Date: Feb 2011
Location: medusa NY
Boat: Tayana Surprise 45 schooner "Union Pacific"
Posts: 2,098
Re: Steel or Aluminum

Sorry for being brief, i am away on business.
The plan for the anti-filing pain and to keep myself from having hull outs, Is to simply beach the boat on sandbars during low tide and work on it then. One small Spot at a time I can apply The anti-fowling paint. I'm not sure if I will ever even have to haul the boat out. Perhaps every 10 years or so for new shaft seals.
But I can only speculate on maintenance and upkeep. It's completely unknown.

Keep in mind I'll be keeping it mostly in freshwater. The bottom paint you last a very long time in those conditions.
__________________
scoobert is offline   Reply With Quote
Old 19-12-2012, 17:19   #100
Registered User

Join Date: Aug 2011
Location: Melbourne Australia
Boat: Paper Tiger 14 foot, Gemini 105MC 34 foot Catamaran Hull no 825
Posts: 1,616
Re: Steel or Aluminum

This Multihull was painted with anti foul paint in one tide change, There were 3 people painting it,

One of the Multihull advantages, No haulouts for maintenance.
Even thru hulls can be repaired or replaced during tide changes,
Attached Thumbnails
Click image for larger version

Name:	Fiji, Sailchute. Fiji Day 029.jpg
Views:	98
Size:	402.2 KB
ID:	51462  
__________________
Mr B is offline   Reply With Quote
Old 20-12-2012, 02:05   #101
Moderator
 
noelex 77's Avatar

Cruisers Forum Supporter

Join Date: Jul 2007
Location: Living on dirt waiting for our new yacht to be built.
Boat: Half built Bestevaer.
Posts: 10,619
Re: Steel or Aluminum

Quote:
Originally Posted by Mr B View Post
This Multihull was painted with anti foul paint in one tide change, There were 3 people painting it,

One of the Multihull advantages, No haulouts for maintenance.
Even thru hulls can be repaired or replaced during tide changes,
Ahhh those 3m Queensland tides a real nuisance, but they can be helpful as well.
Not many places worldwide have these sort of tides, however.
Even fewer in freshwater
__________________
noelex 77 is offline   Reply With Quote
Old 20-12-2012, 07:19   #102
Registered User

Join Date: Aug 2011
Location: Melbourne Australia
Boat: Paper Tiger 14 foot, Gemini 105MC 34 foot Catamaran Hull no 825
Posts: 1,616
Re: Steel or Aluminum

Quote:
Originally Posted by noelex 77 View Post
Ahhh those 3m Queensland tides a real nuisance, but they can be helpful as well.
Not many places worldwide have these sort of tides, however.
Even fewer in freshwater
Hahahahahaha, That was Muscat Cove in Fiji, Less than 2 metre tide, He would have just scraaaaaaaaped on there at high tide,

I wouldnt take my Gemini across there At full tide,
I missed my boat in the dark one night and ran aground on there with my dinghy, Hahahahahaha

They have a 10 metre tide in the Kimberlys, With a 3 metre tidal wave going in and out of the gorges, You have to be on the ball up there,
__________________
Mr B is offline   Reply With Quote
Old 20-12-2012, 13:36   #103
Senior Cruiser
 
44'cruisingcat's Avatar

Cruisers Forum Supporter

Join Date: Sep 2006
Posts: 7,454
Images: 69
Re: Steel or Aluminum

Quote:
Originally Posted by scoobert View Post
Its ok belief is not required, nor is percipatation.
You are 100% correct. An electric motor has maxium torque at 0 rpm and that does not calculate to hp rating. I am not here to give an engeneering class.

When the steel cat does run into rocks or whatever, it will take a lot of force to penetrate 1/4" steel.

Sent from my iPhone
When the steel cat runs onto rocks it's weight and momentum will generate a lot of force.
__________________
44'cruisingcat is offline   Reply With Quote
Old 20-12-2012, 19:35   #104
Senior Cruiser
 
hpeer's Avatar

Cruisers Forum Supporter

Join Date: Dec 2008
Location: Philadelphia
Boat: Murray 33-Chouette & Pape Steelmaid-44-Safara-both steel cutters
Posts: 3,900
Re: Steel or Aluminum

Here's a great site about home building a 65' mono. Not as big a job as a 65' cat, but will give you an idea of what is involved.


Fascinating stuff, great videos

http://www.submarineboat.com/sailboat.htm
__________________
hpeer is offline   Reply With Quote
Old 21-12-2012, 06:30   #105
cruiser

Join Date: Feb 2011
Location: medusa NY
Boat: Tayana Surprise 45 schooner "Union Pacific"
Posts: 2,098
Re: Steel or Aluminum

Quote:
Originally Posted by Mr B View Post
Hahahahahaha, That was Muscat Cove in Fiji, Less than 2 metre tide, He would have just scraaaaaaaaped on there at high tide,

I wouldnt take my Gemini across there At full tide,
I missed my boat in the dark one night and ran aground on there with my dinghy, Hahahahahaha

They have a 10 metre tide in the Kimberlys, With a 3 metre tidal wave going in and out of the gorges, You have to be on the ball up there,

up here on the Hudson we may not have a huge tide, but it is fresh water, mind the sewage, and its enough time to make progress on the hull paint.
__________________

__________________
scoobert is offline   Reply With Quote
Reply

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 01:12.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.