Do you want to be informed on new Posts on this Thread? (members only)

Keel Bolts and General Topics on Keel - ICOMIA Keel Checker
04 April 2015 - 19:13
#1
Join Date: 01 February 2007
Posts: 234

ICOMIA Keel Checker
I have recently been on the website which has a spread sheet and checks if your keel meets todays very high standards of design.
The website is www.icomia.com
If any technical people out there feel upto a technical challenge and would like some reassurance about our keel designs perhaps the site is worth a look.

John B
Swan 411 010

05 April 2015 - 14:55
#2
Join Date: 30 January 2007
Posts: 440

Thank you John, interesting to know and I would like to hear comments by Lars.
I also have some comments although I aknowledge that they may be naif and a bit biased; I ask you all to please forgive me in advance for my polemical attitude!
First: I was already presumptuously certain that the keels designed by S&S and built by Nautors were very well made and did not need a confirmation of this from ICOMIA.
Second: I sort of aprioristically distrust something that calls itself International Council of Marine Industry Associations and
Third: I do not think that it is fair that everything seemingly interesting for the general public and possibly useful to increase the safety is for sale and not free on their site.

Happy Easter to everybody; to myself I add: take it easy!!! :-)
Daniel, 411/004.

05 April 2015 - 15:55
#3
Join Date: 01 February 2007
Posts: 234

Daniel, I agree with the assumption that we have no problems with the attachment of our keels.

I thought this would be of a bit of interest and amusement to see how our yachts compared to supposedly modern designs which should by definition have be improved upon.

John B

06 April 2015 - 14:23
#4
Join Date: 02 January 2008
Posts: 1428

Dear John and Daniele
ISAF governs the safety for offshore sailing, and a few years ago they got very concerned as there were some keels dropping off on fairly new boats, and investigations not unexpectedly showed that this occurred particularly for keels with short attachments against the hull.
The working group for ISO standard 12215-9 Appendage Attachments was therefore instructed to develop a tool for calculating the proper scantlings, resulting in the Keel Checker.
The calculation requires detailed input, but also determines the loads quite in detail.
As far as I know it is freeware, but can not be recommended for everybody as it requires very good knowledge of the structural arrangements for keel attachment.
I would suggest that the fairly long keel attachments using many bolts on S&S Swans should meet the requirements for Load Case 1 i.e. sailing, but probably Load Case 4 grounding at speed is not met.
I have been a beta-tester evaluating this tool for newer designs, and would be available to do calculations providing older information is available.
Kind regards
Lars

15 April 2015 - 15:26
#5
Join Date: 02 January 2008
Posts: 1428

Further on this matter:
I did a calculation for Swan 411 keel bolts with partly estimated input, and got the Compliance Factor 0.9 for Load Case 1 heeled to 90 degrees. This means a 10% increase would bring compliance, and a more accurate center of gravity location as well as keel weight are of interest here.
Interested owners could kindly measure the lead keel maximum thickness at the top, and at the bottom (at the upper edge of the V-shape), as well as the lengths of the four keel edges, and a diagonal from the lower fwd tip to the upper aft edge, this enables weight and cg to be worked out. The bilge recess at the aft end of the keel should be ignored, i.e. assume the forward top of lead line to continue right aft.
If somebody has a keel lines drawing this would be a great help :-)
It can be pointed out that the bolt loads at normal sailing angles are one half of the loads at 90 degrees heel, and the loads are further reduced by the keel lift forces acting while on the wind.
Kind regards
Lars

16 April 2015 - 11:52
#6
Join Date: 01 February 2007
Posts: 234

Lars, very interesting and many thanks. I am away in Africa for some time so cannot assist with measurement. Hopefully others can so you can conclude this very interesting topic.

16 April 2015 - 13:34
#7
Join Date: 30 January 2007
Posts: 440

Dear Lars,
among my documents I do have a high resolution scan of the water lines of the 411 with the keel and I will be very glad to send it to you. I am sure that even if I had to sign some document when I purchased the blueprint, the S&S office in New York will have nothing to complain of if I send it to Lars Strom... :-)
Daniel, 411/004

24 April 2015 - 12:42
#8
Join Date: 02 January 2008
Posts: 1428

Dear John
Further to the keel bolts.
The drawing Daniele kindly shared shows the original keel, but there is a CG and weight written in afterwards for the deeper and heavier modified keel. Using the latter numbers the Keel-Checker arrives at a Compliance Factor of 0.79 at 90 degrees of heel.

Would suggest that you find out the exact diameter at the bottom of the keel bolt threads, as Keel-Checker uses a safe approach in several respects, and for example assumes the coarsest thread with the smallest root diameter. In case you have a finer thread this immediately improves compliance.
Kind regards
Lars

24 April 2015 - 22:10
#9
Join Date: 01 February 2007
Posts: 234

Lars, all swan owners sorry but I am in Africa for some time so cannot help.
Hopefully other Swan owners can come to the rescue with the information required. This seems to me to be a very interesting topic as we all assume our keels and design / engineering is better than today's design.
John B
Swan 411 010

30 May 2015 - 13:59
#10
Join Date: 01 February 2007
Posts: 234

Lars I am now back and Avista still out of the water. Can you just confirm in not too technical language what further measurements you require. Some time back when re-working my mast step I took these photos. The lifting plate further aft which was a huge steel triangle I have removed as it was always very rusty. I replaced these with 3 very large S/S washers as you see in the photo.

I see the MAIB report on Cheeki Rafiki is out with a number of interesting observations.

30 May 2015 - 14:25
#11
Join Date: 01 February 2007
Posts: 234

30 May 2015 - 19:41
#12
Join Date: 02 January 2008
Posts: 1428

Dear John
Thank you for the pictures
There are two bolt measurements that may affect the compliance in this case:
1. the thread pitch used for the M24 and M20 bolts. A gauge is needed for measuring this.
2. for the keel bolt pairs the transverse distance between the bolt centers.
Also, the keel bolt nuts need to be locked in a reliable way.

There are also requirements for the backing plates.
For M24 bolts the backing plate area needs to be 11821 sq.mm., for example a round washer with 121 mm diameter meets this, or a square with 109 mm sides, or a rectangle with the same area.
If the bolt center is further than 60 mm from the nearest keel floor the backing plate thickness needs to be 18.6 mm, if closer than 60 mm 12.4 mm thickness would be sufficient.
Kind regards
Lars

31 May 2015 - 00:07
#13
Join Date: 30 January 2007
Posts: 440

Dear John,
can I ask you to please put a length reference close to the bolts?
At a first sight those bolts do not look like 20 or 24 mm diameter.
Daniel, 411/004 Luna Menguante

27 June 2015 - 23:07
#14
Join Date: 01 February 2007
Posts: 234

We have been working on the details off line and I think we can confirm that certainly the 411 would NOT meet todays standard of attaching keel to hull. This is mainly due to the thickness and size of washers used on the bolts. They do however comply with Lloyds 1001A standards. As I know of no cases where S&S Swan keels fall off sailing and seemed to have survived many a crash I think we do not have to worry too much. It has been a very interesting topic with many more questions raised. Are the new standards higher or just different? Why did Swan attach a lead keel with stainless bolts to the hull as Bronze is recommended?

28 June 2015 - 18:18
#15
Join Date: 02 January 2008
Posts: 1428

Dear John
The new standard additionally considers grounding loads, and attempts to cover all possible strength aspects particularly for the washers.
Bronze bolts are recommended specifically for wooden yachts, but stainless bolts are an acceptable alternative for GRP hulls provided they are properly embedded in mastic.
Lloyd's Register was actively involved in the material choices for the early Swan models through the Chief Surveyor in Finland ke Lindqvist who used to do yard inspections together with Rod Stephens.
Kind regards
Lars

10 September 2015 - 09:23
#16
Join Date: 02 January 2008
Posts: 1428

Dear John and Daniele
Further on the subject of keel attachment:
Had the opportunity to compare Swan 44 keel bolts to the ISO-standard, and the result is a Compliance Factor of 2.24 over the standard for transverse loads, and 3.66 for longitudinal loads.
Kind regards
Lars

11 December 2015 - 17:52
#17
Join Date: 01 February 2007
Posts: 234

Lars, given that a new Oyster 825 recently sank after losing its keel, I am quietly confident after 36 years afloat the chance of anything falling off my yacht are pretty remote.
I am sure the new Oyster would have complied with all new build regulations. It is in the process of being raised for investigation, so it will be interesting to discover the cause.

I will however be increasing the size of the washers.
JUST IN CASE!

John B
411 010

12 December 2015 - 21:16
#18
Join Date: 02 January 2008
Posts: 1428

Dear John
The yacht you mention has been salvaged, and photos can be found on the internet.
Based on them I would suggest that the structure does not meet the regulations, but I leave it to the investigators to report what happened.
Kind regards
Lars

13 December 2015 - 17:30
#19
Join Date: 01 February 2007
Posts: 234

Dear Lars, shocking reading the reports on what happened to that yacht and its owner and crew. For those interested go to the website below.

www.wavetrain.net

I followed through the Russian publication also in the article.

  • Threads : 1500
  • Posts : 8927
  • Members: 750
  • Online Members: 3