Boat Design Forums  |  Boat Design Directory  |  Boat Design Gallery  |  Boat Design Book Store  |  Thanks to Our Site Sponsors
  #1  
Old 07-26-2016, 02:48 PM
BertKu BertKu is offline
Senior Member
 
Join Date: May 2009
Rep: 223 Posts: 2,193
Location: South Africa Little Brak River
Folding up keel.

I am busy making this different type of keel.
Here are my problems.
1) Should I place a permanent keel on my boat, I have to modify my trailer, which I don’t like to do.
2) If my experimental folding in keel is a success, I am then also able to sail in less deep water.
3) With a gadget it will be retractable before loading on the trailer.

This is what I am building for my boat. It is an experiment. I don’t think it is ever done in the world. I think the drawings are self explainable. However if you consider I should make a change or improvement. I am gladly open for comment
Bert
Attached Thumbnails
Folding up keel.-folding-up-keel2.jpg  Folding up keel.-folding-up-keel.jpg  

Last edited by BertKu : 07-26-2016 at 02:52 PM. Reason: Some corruption was removed.
Reply With Quote
  #2  
Old 07-26-2016, 02:57 PM
upchurchmr upchurchmr is offline
Senior Member
 
Join Date: Feb 2011
Rep: 579 Posts: 2,365
Location: Ft. Worth, Tx, USA
What kind of a boat?
A rectangular keel will have very poor drag.
How does it come up?

That is not much lead.
Reply With Quote
  #3  
Old 07-26-2016, 05:29 PM
rwatson's Avatar
rwatson rwatson is offline
Senior Member
 
Join Date: Aug 2007
Rep: 1749 Posts: 4,913
Location: Tasmania,Australia
"Should I place a permanent keel on my boat,"

I dont know. If it hasnt got one, why put it on ??
__________________
For every action, there is an equal and opposite criticism. "
Reply With Quote
  #4  
Old 07-27-2016, 02:56 AM
daiquiri's Avatar
daiquiri daiquiri is offline
Engineering and Design
 
Join Date: May 2004
Rep: 3380 Posts: 5,352
Location: Italy (Garda Lake) and Croatia (Istria)
How do you actuate the keel extension? Looks like manual work, before launching the boat?
Reply With Quote
  #5  
Old 07-27-2016, 03:24 AM
BertKu BertKu is offline
Senior Member
 
Join Date: May 2009
Rep: 223 Posts: 2,193
Location: South Africa Little Brak River
Quote:
Originally Posted by upchurchmr View Post
What kind of a boat?
A rectangular keel will have very poor drag.
How does it come up?

That is not much lead.
The boat is a 16 feet cabin boat with 2 extension at the transom to hold the solar panels and frame work.
Photo's attached. Bert
Attached Thumbnails
Folding up keel.-photo0191.jpg  
Reply With Quote
  #6  
Old 07-27-2016, 08:23 AM
BertKu BertKu is offline
Senior Member
 
Join Date: May 2009
Rep: 223 Posts: 2,193
Location: South Africa Little Brak River
Quote:
Originally Posted by daiquiri View Post
How do you actuate the keel extension? Looks like manual work, before launching the boat?
Hi Daiquiri, I was hoping that you would comment. I have great respect for your engineering abilities. As you can see from the photo's the transom extension is permanent. It adds 180 liter of buoyance. I needed it, due to the weight for my batteries, which is 100kg.
The extensions for the keel is done by 35 kg force spring blades. You can see the stipple line in the drawing. The weight of the boat will compress it to 3 into 1. (and I planning to build a gadget to raise and lower the extensions from the steering wheel, see photo)
Guys, see it my way. I am not interested in speed and doing 20 knots. If I do 1 knot more than the current and wind, I am happy. Thus my speed is only approx. 5 knots. It is the wrong hull, we all know that. But it has a seaworthy certificate. Which I, after the modifications are totally finished, have to renew. However to place a small jib and a mast on the boat, I need a small keel, otherwise the boat will start drifting. Also because I place a mast and jib (No mainsail) on the boat, my CG is changing and I need to bring it lower down. Thus with this metal folding keel, with a possibility to add some lead to the keel, I should accomplish that. The only thing I am worried about is, should I hit a rock, what damage would have been done, not to enable me to lift the keel up. Maybe your engineering thoughts are welcome.
Bert
Attached Thumbnails
Folding up keel.-097.jpg  Folding up keel.-098.jpg  Folding up keel.-101.jpg  


Last edited by BertKu : 07-31-2016 at 10:37 AM. Reason: Wrong english word. Replaced by accomplish
Reply With Quote
  #7  
Old 07-27-2016, 08:25 AM
BertKu BertKu is offline
Senior Member
 
Join Date: May 2009
Rep: 223 Posts: 2,193
Location: South Africa Little Brak River
Quote:
Originally Posted by rwatson View Post
"Should I place a permanent keel on my boat,"

I dont know. If it hasnt got one, why put it on ??
Hi RWATSON, nice to see you are still around. I need a keel otherwise the boat will start drifting. Bert
Reply With Quote
  #8  
Old 07-27-2016, 08:31 AM
BertKu BertKu is offline
Senior Member
 
Join Date: May 2009
Rep: 223 Posts: 2,193
Location: South Africa Little Brak River
Quote:
Originally Posted by upchurchmr View Post
What kind of a boat?
A rectangular keel will have very poor drag.
How does it come up?

That is not much lead.
It is just a possibility for me, to add some lead. In principle I don't need the lead, just the keel not to drift with a small jib only.
Bert
Reply With Quote
  #9  
Old 07-28-2016, 12:52 AM
portacruise portacruise is offline
Senior Member
 
Join Date: Jun 2009
Rep: 218 Posts: 979
Location: USA
Scroll down to folding bilge keel, looks to be lower profile: http://www.submarineboat.com/keels.htm

Hope this helps, Bert.

PC
Reply With Quote
  #10  
Old 07-28-2016, 02:05 AM
PAR's Avatar
PAR PAR is offline
Yacht Designer/Builder
 
Join Date: Nov 2003
Rep: 3967 Posts: 17,895
Location: Eustis, FL
I'd agree, bilge keels would be a better solution. They can be arrange to not increase draft or at least not very much, will offer effective lateral area and will have no moving parts.





This are good examples of twin bilge keels that aren't any deeper than the belly of the boat, but dramatically increase lateral area, while still retaining the shoal nature of the boat.

Do you have a photo of the boat's bottom, so we can see where they might be best placed? If not, how about a make, model and year, so we can pull it up and have a look?
Reply With Quote
  #11  
Old 07-28-2016, 02:34 AM
daiquiri's Avatar
daiquiri daiquiri is offline
Engineering and Design
 
Join Date: May 2004
Rep: 3380 Posts: 5,352
Location: Italy (Garda Lake) and Croatia (Istria)
BertKu, I agree with PAR and Portacruise. You are designing a mechanism which will sooner or later become a victim of corrosion and marine growth, if the boat is intended to stay in water for some periods of time. Besides that, telescopic systems are problematic when it comes to mechanical stability and resistance (both in operation and in case of collision with ground), and to watertightness.
Technically it can be done, but it is IMO not a sound (nor cheap) solution. I would go for a fixed short ballasted keel, either a bilge type or a full-length one.
Cheers
Reply With Quote
  #12  
Old 07-28-2016, 03:54 AM
BertKu BertKu is offline
Senior Member
 
Join Date: May 2009
Rep: 223 Posts: 2,193
Location: South Africa Little Brak River
Quote:
Originally Posted by daiquiri View Post
BertKu, I agree with PAR and Portacruise. You are designing a mechanism which will sooner or later become a victim of corrosion and marine growth, if the boat is intended to stay in water for some periods of time. Besides that, telescopic systems are problematic when it comes to mechanical stability and resistance (both in operation and in case of collision with ground), and to watertightness.
Technically it can be done, but it is IMO not a sound (nor cheap) solution. I would go for a fixed short ballasted keel, either a bilge type or a full-length one.
Cheers
Thank you Daiquiri, The cost is very little, I could make it for USA$ 46.00 I use stainless steel off cuts. But you are right my worry concerning a hit is the real problem. Porta, has also given me a nice solution
http://www.submarineboat.com/images/...ged_Keel_2.JPG So did PAR. Well let see what I am going to do. First I complete my front jib and mast and then worry about drifting and keels. Thanks all of you. Bert
Reply With Quote
  #13  
Old 07-28-2016, 03:55 AM
CDK's Avatar
CDK CDK is offline
retired engineer
 
Join Date: Aug 2007
Rep: 1819 Posts: 3,277
Location: Adriatic sea
Bert, instead of the telescopic approach that -as daiquiri wrote- is asking for trouble, you could make a hinged keel. Two swivel points, firmly attached to the hull with large backing plates to distribute the forces in case the keel hits something.
On the trailer, the keel lies flat; after launching gravity pulls it down and you lock it with two large pins from inside the boat. The locking pins slide in guiding tubes that reach above the waterline so your cabin stays dry.
__________________
cogito, ergo sum (Descartes' credo)
Reply With Quote
  #14  
Old 07-28-2016, 04:52 AM
PAR's Avatar
PAR PAR is offline
Yacht Designer/Builder
 
Join Date: Nov 2003
Rep: 3967 Posts: 17,895
Location: Eustis, FL
I've seen folding bilge keels that did this too CDK.
Reply With Quote


  #15  
Old 07-28-2016, 09:07 AM
BertKu BertKu is offline
Senior Member
 
Join Date: May 2009
Rep: 223 Posts: 2,193
Location: South Africa Little Brak River
Quote:
Originally Posted by PAR View Post
Do you have a photo of the boat's bottom, so we can see where they might be best placed? If not, how about a make, model and year, so we can pull it up and have a look?
Hi PAR, here 3 photo's of the bottom. Maybe another crazy idea from me, but I have placed 2 tyres not in line, but narrower. If I hit a pothole and that has happened a number of times here around, at least I don't pick up a blown tyre. What do you think what I should do for what kind of keel. Bert
Attached Thumbnails
Folding up keel.-bottom1.jpg  Folding up keel.-bottom2.jpg  Folding up keel.-bottom3.jpg  

Reply With Quote
Reply



Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
52' folding boat philSweet Boat Design 2 04-07-2016
03:35 PM 
skeg/keel cutaway vs solid full keel on inboard Double Eagl Northeaster Inboards 20 02-13-2016
06:51 AM 
Another type of folding keel Chris Ostlind Sailboats 1 04-14-2006
05:38 PM 
Folding Toilet!! lordrailie Boat Design 2 10-27-2004
07:14 AM 
folding boat wyomoose Wooden Boat Building and Restoration 3 04-18-2004
10:22 PM 

Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.

All times are GMT -5. The time now is 03:31 PM.


Powered by: vBulletin Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Web Site Design and Content Copyright ©1999 - 2017 Boat Design Net