Bow thruster - theoretizing :) - Page 2 - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > On Board > Gear & Maintenance
 Not a Member? 
  #11  
Old 07-06-2008
camaraderie's Avatar
moderate?
 
Join Date: May 2002
Location: East Coast
Posts: 13,878
Thanks: 0
Thanked 2 Times in 2 Posts
Rep Power: 15
camaraderie is a jewel in the rough camaraderie is a jewel in the rough camaraderie is a jewel in the rough
Brak...here is the echo charger.
Xantrex Technology Inc. - echo~charge - Product Information
Usually used to keep a starter battery topped up but would work longer term for charging a small bank for a thruster.
__________________
No longer posting. Reach me by PM!
Reply With Quote Share with Facebook
  #12  
Old 07-06-2008
Sea Slacker
 
Join Date: Jan 2007
Posts: 1,789
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 8
brak is on a distinguished road
Quote:
Originally Posted by camaraderie View Post
Brak...here is the echo charger.
Xantrex Technology Inc. - echo~charge - Product Information
Usually used to keep a starter battery topped up but would work longer term for charging a small bank for a thruster.
Excellent. Thanks!

My starter is sitting on a regular ACR, but this thing seems to be very much on the money.

Ok. So all I've got to do now is come up with some small change, and we are in business.
Reply With Quote Share with Facebook
  #13  
Old 07-07-2008
SVAuspicious's Avatar
Mermaid Hunter
 
Join Date: Oct 2006
Location: on the boat - Chesapeake
Posts: 2,956
Thanks: 0
Thanked 56 Times in 46 Posts
Rep Power: 8
SVAuspicious will become famous soon enough
Quote:
Originally Posted by brak View Post
I have Hallberg-Rassy 35, it is listed in my profile. Without going too far into this discussion (and leaving aside my sailing abilitiy), I can only say that there are certain things that cannot be done with a full keel single screw vessel with hydraulic steering. For example - it is not possible to make a 90 degree turn to starboard when confined in a fairway of less than about 60'. It is also not possible to use reverse to control turning. That is something that drivers of fin keel flat bottom boats
I have an HR 40. Clearly there are big differences between the Enderlein boats and the Frers boats.

I don't mean to impugn your abilities. I do have some experience on full keel boats, mostly Cape Dory and Allied boats.

I'm surprised at the limitations on turning to starboard -- do you have a LH prop? Have you tried looking for handling suggestions on the UK HROA site? Can you not use propwalk to move the boat? Propwalk is helpful on my boat, but on the full-keelers I have sailed it is critical.

The Rasmus has a great reputation. I'm sure you are very happy with her.

sail fast, dave
Reply With Quote Share with Facebook
  #14  
Old 07-07-2008
Sea Slacker
 
Join Date: Jan 2007
Posts: 1,789
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 8
brak is on a distinguished road
Quote:
Originally Posted by SVAuspicious View Post
I have an HR 40. Clearly there are big differences between the Enderlein boats and the Frers boats.

I don't mean to impugn your abilities. I do have some experience on full keel boats, mostly Cape Dory and Allied boats.

I'm surprised at the limitations on turning to starboard -- do you have a LH prop? Have you tried looking for handling suggestions on the UK HROA site? Can you not use propwalk to move the boat? Propwalk is helpful on my boat, but on the full-keelers I have sailed it is critical.

The Rasmus has a great reputation. I'm sure you are very happy with her.

sail fast, dave
I've seen new HR's and even sailed on a large one a few years ago I was able to back it and dock mediterranean style not using bow thrusters (which it had available), this was part of the our charter/study course. These boats have all the characteristics of modern sailboat, including very reasonable steering. They are also VERY nice I would not mind owning one at all

As far as turns go, I think turning to port would be the same - it is just that my slip is to stbd. The distance available is simply not enough to perform full 90 degree turn at any speed.

When moving in reverse, boat turns counterclockwise. I duscussed this here previously - I have no explanation for the direction (the prop is right handed as far as I know, and I was told that the behavior should be exactly opposite) but it is what it is, in reverse at speeds of less than about 3kts steering is inoperative and boat turns counterclockwise at her own pace. I guess that does make stbd turns more challenging as I can't back out while turning clockwise, and continue.

This is exacerbated by my slip being very narrow (about 12-13' for a 11' beam). Certainly wider slip facing open water would be a simpler solution

But you know, I can dream of a bow thruster too. It's on the same list on which I have a radar, a wind instrument and solar panels

P.S. I may not know right from left, but my pre-purchase survey noted this: "Propeller, three blade 16 RH 12". That's right-handed, I think.

Last edited by brak; 07-07-2008 at 12:38 PM.
Reply With Quote Share with Facebook
  #15  
Old 07-07-2008
tomaz_423's Avatar
Senior Member
 
Join Date: Feb 2006
Location: Slovenia
Posts: 410
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 9
tomaz_423 will become famous soon enough
At least once on this site I can read Beneteau and fin keel boats are better! At least for something.
Yeah, I can turn my Bene 423 (or similar fin keel boats) in circles (be it left or right) in less then two boat lengths. Only a strong wind prevents me from pushing the bow through the wind with simple forward-and-reverse engine action and rudder all the way to one side.

My first idea for your problem was:
Use existing windlass cables (or double them if needed), lead the control lines for the windlass and for the thruster forward (3 small wires) and have the large windlass and thruster switch forward. Even if the wires are a bit too small and start to overheat - it is only a 30 sec. blast, so the danger of fire is not that big. Even if there is a significant voltage drop with undersized wires - it is still a voltage drop from 14.2V (engine is running if you use thruster) and not from 12.4V. But then I calculated what a small draw your windlass have and i decided not to suggest anything. As it is not going from 1,2 Kw windlass to 2 KW thruster - it is much bigger difference.

If you have a small battery forward perhaps you could still use existing windlass cables (this is not tested, it is just a thought):
1) Connect the forward small battery and your starter battery (or house batteries if they are of the same type) with your existing windlass cables.
2) install the control lines for the windlass and the thruster with power switches (solid stare of you can get that strong or a relay) close to the forward battery.
3) Connect the windlass and the thruster to the forward battery (over the control switch)
Normally: the forward battery and the main battery have similar voltage and no large current is drawing through the long existing cables
At windlass operation: there is some voltage drop at forward battery, so some A are flowing from main to forward battery, but in no case is that current larger then you have now without the battery, so it is OK.
At thruster operation: The thruster is a significant load for the forward battery, so the voltage drops substantially. The voltage at main battery was the same as before, so the is a voltage difference at the cable, which creates electrical current. The power burned at the cables and the power burned at the thruster are proportionate to the voltage drop.
Let us say you have 2KW thruster, 14V at main battery and 12 volt at forward battery. The power (resulting in cable heating) is about 333 W, which will not melt anything - the 333W is consumed over the length of 2 X 30 (or so) feet, on the strong and heavy cables. They will get a bit hot, but you do not want to run the thruster for 30 minutes, just bursts of 30 seconds. I am too lazy to calculate how much warmer your cables will get in 30 seconds, but my guess is just a few degrees. As soon your thruster is not operating the V on the forward battery will recover closer to previous state, so the current through cables will be smaller.
Again: Please note this is not a tested or recommended solution, it is just some loud thinking of an amateur with some basic knowledge about electricity and some math skills.
What do others think about this ? would it burn down the beautiful HR or would it work (and improve windlass operation as byproduct)?
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Beneteau Oceanis 473

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

full time cruising
Reply With Quote Share with Facebook
  #16  
Old 07-07-2008
Pamlicotraveler's Avatar
Senior Member
 
Join Date: Aug 2006
Location: Creedmoor NC
Posts: 554
Thanks: 1
Thanked 0 Times in 0 Posts
Rep Power: 8
Pamlicotraveler is on a distinguished road
Quote:
Originally Posted by brak View Post
But you know, I can dream of a bow thruster too. It's on the same list on which I have a radar, a wind instrument and solar panels .
Brak...

Be empathetic and understanding of SVAuspicious. I believe he suffers from a syndrome defined in the DSM-IV as "bow-thruster envy." When you have that thing put in there use it whenever you can use it to help you. There will always be someone at the dock yelling "cheater" from the dock. Some of my best sailling friends have this BTE disease, it's dreadful.

My philosophy is anything I can do to keep from crashing in to the pilings is a good thing.
__________________
Twenty years from now you will be more disappointed by the things y%^&*.....oh never mind. 90% of the people on sailing forums already use that as their signature! I'm not a conformist.
Reply With Quote Share with Facebook
  #17  
Old 07-07-2008
Pamlicotraveler's Avatar
Senior Member
 
Join Date: Aug 2006
Location: Creedmoor NC
Posts: 554
Thanks: 1
Thanked 0 Times in 0 Posts
Rep Power: 8
Pamlicotraveler is on a distinguished road
Incidentally, Bob Perry told me he had done some testing and that the hull modifcation for a bowthruster resulted in a very minimal decrease in speed. He said it was negligible.
__________________
Twenty years from now you will be more disappointed by the things y%^&*.....oh never mind. 90% of the people on sailing forums already use that as their signature! I'm not a conformist.
Reply With Quote Share with Facebook
  #18  
Old 07-07-2008
Sea Slacker
 
Join Date: Jan 2007
Posts: 1,789
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 8
brak is on a distinguished road
This ain't no religious fight over purity of sailing

I motor around most of the time cuz there is either no wind or I am too lazy to bother going to the mast and raising the main So, I am probably the last person to care about anything being done "the sailing way" or not.

That said, this is all theory for now. I have a hard top project going on and until that is done and paid for, no other major modifications are in plans.
Reply With Quote Share with Facebook
  #19  
Old 07-07-2008
Owner, Green Bay Packers
 
Join Date: Sep 2006
Location: SW Michigan
Posts: 10,318
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 11
sailaway21 is just really nice sailaway21 is just really nice sailaway21 is just really nice sailaway21 is just really nice
Your unwillingness to part with any of your well publicised riches is making it difficult for us to remain actively involved in this project.









__________________
“Scientists are people who build the Brooklyn Bridge and then buy it.”
Wm. F. Buckley, Jr.
Reply With Quote Share with Facebook
  #20  
Old 07-07-2008
poopdeckpappy's Avatar
Senior Member
 
Join Date: Jul 2006
Location: San Diego
Posts: 5,533
Thanks: 23
Thanked 38 Times in 32 Posts
Rep Power: 10
poopdeckpappy has a spectacular aura about poopdeckpappy has a spectacular aura about
Quote:
Originally Posted by brak View Post
I have a hard top project going on and until that is done and paid for, no other major modifications are in plans.
Good, by that time you'll realize that BT's are a waste of money for ya

As someone who has a 37' full keel sailboat, who has a hard 90 to port followed very quickly by a hard 90 to starboard to get to his double wide slip that has nothing seperating me from the boat next to me, in a fairway less than 60', I can tell you to save your money for better things than BT's

Spend the time to learn how the boat reacts to your input though the controls and you'll be surprised at what you can do within reason, or in a emergency. I will never get my Tayana to turn within it's own length like I do with our 45' hunter, but I can get it to do a 180 in a fairway less than 60' and it's 42' overall including bowsprit; and I'm no sailing wizard.
__________________
1978 Tayana 37

Freedom comes when you’re ready to sail away. True freedom comes when you don’t have to return


Cut off from the land that bore us, betrayed by the land we find, where the brightest have gone before us and the dullest remain behind, .......but stand to your glasses, steady,.......tis all we have left to prize, raise a cup to the dead already, hurrah for the next that dies
Reply With Quote Share with Facebook
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Low buck bow thruster?? wildcard Gear & Maintenance 48 12-23-2013 08:09 PM
Interesting Bow Thruster Topic from Tommy Solomon luckyjim Tartan 1 08-19-2007 11:35 PM
Bow thruster Artwerke Gear & Maintenance 2 06-15-2006 03:58 PM
bow thruster installation Myblueheaven Gear & Maintenance 1 09-10-2004 02:26 AM
The Basics of Doing the Bow Rich Bowen Racing Articles 0 03-20-2002 07:00 PM


All times are GMT -4. The time now is 07:55 AM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.