Marine structural engineer ? for boat extension.

[W+T]

Hi all

Some may know i have a Norman 32 which i will extending to 44 foot by making the middle extension myself, unless i can get another Norman of same profile to do it then Cut n Shut it.

BUT this question is about me making my own extension. It would go both ways i guess with either Cut n Shut or new extension.


I have plans in my head on what i am going to do to make this work with the stringers and bearers etc to join the extension.

So can anybody advice a local and good structural boat/Marine engineer around Manchester i can go to with my plan to see what they can advice and think of it. 


Admiral Faffer 

 

[ditchcrawler]

Not in the area you want but there is a stretched glass fibre boat at Lyons yard on the N Stratford

[WotEver]

If you message Mads on the YouTube Sail Life channel he might advise you which structural engineer he used when beefing up the stringers on his yacht. It was all done by email I believe. 

[W+T]

21 minutes ago, ditchcrawler said:

Not in the area you want but there is a stretched glass fibre boat at Lyons yard on the N Stratford

 

 

10 minutes ago, WotEver said:

If you message Mads on the YouTube Sail Life channel he might advise you which structural engineer he used when beefing up the stringers on his yacht. It was all done by email I believe. 

 

Yes i guess i dont need anybody to come and see the boat but just the plans. 

 

Not sen Mads for a few weeks as been so busy, need a catch up. 

[Momac]

Sounds like you need a Naval Architect .

 

The new middle bit needs to be significantly more robust than the bits at each end.

[Alan de Enfield]

2 hours ago, W+T said:

So can anybody advice a local and good structural boat/Marine engineer around Manchester i can go to with my plan to see what they can advice and think of it. 

The RYA is the 'notified body' for the RCD in the UK.

Part of the RCD requirements for boats is the structural strength requirements - maybe the RYA could suggest some names of the structural examiners that are registered with the RYA

 

One of the PCA (Post Construction Assessors) may be the one you want to advise you as they are used to working with a boat 'already in existence'.

 

Examples :

 

Although there may be standards or parts of standards that relate to the integrity and structure of component parts of craft, RSG has
interpreted the Essential Requirements as relating to the integrity and structural requirements of the hull, deck and superstructure. This
includes construction and attachment of items such as keel, rudder, chain plates and other strength critical items as appropriate.
To assess the structural integrity, one of the following approaches shall be considered:
1. Application of appropriate parts of EN ISO 12215, provided that the scantlings derived from draft parts of the standard are checked
by one of the methods described below. Appropriate documentation shall be developed.
2. The structural requirements of the hull may be assessed by other acceptable scantling determination methods that are applicable
to the boat type, design category and the Manufacturer's maximum recommended load. Appropriate documentation shall be kept.
3. As an alternative to acceptable scantlings determination methods or in cases where no applicable rules exist, acceptable
construction calculation(s) or testing may be used. Calculations and proof of testing shall be documented.
4. In particular cases and if acceptable empirical knowledge can be demonstrated as to the structural requirements of the hull, this
may be used as an alternative to the previous methods outlined. This shall include relevant documentation.
Appropriate documentation supporting the methods used shall be developed.
If applicable the following shall be included when drafting the appropriate documentation:
1. Scantling determination method
• Description of the acceptable scantling determination method used for assessment
• Description of material, principle of structure and scantlings for the case
• Input values for strength and stiffness of materials used
• Input and output calculation results on the different structural members
2. Calculation and/or testing
• Description of case
• Reference to applied calculation method (loads, materials, geometry, analysis principle)
• Evaluation and statement of the applicability of the method for assessment
• Input and output calculation results on the different structural members
• Description of test methods and their applicability for the case
• Test results and their validity for assessment purposes
3. Empirical knowledge
• Description of case
• Description of applicability of the empirical material used for assessment
• Documentation of empirical records (information of conditions of use in relation to intended design category, failures, reclamation,
tests, etc.)
• Documentation of transposition method used from the empirical data to actual use
• Assessment of the case in relation to empirical knowledge according to method described.
For structural requirements of opening appliances, see EN ISO 12216 – Small Craft - Windows, port lights, hatches, deadlights and doors -
Strength and tightness requirements (see Annex I.A.3.4).

[Bee]

Trying to blend in the old with the new could be really difficult if you make it yourself. Obviously the original bits were made in a mould but unless you were really careful and used a kind of external mould with hardboard or something and a heck of a lot of bracing you will end up with a bit of a mess and a couple of boat ends. So far as strength is concerned  then the answer is lots of long fore and aft stringers up the sides and some good deep stringers along the bottom and long stringers under the deck. You could have a problem with twist as well if you are thinking of a long centre cockpit. Its a really interesting project but is it worth it? Our boat is 32` but 11.5` wide and we live on it for half the summer, its a bit tight but we see all the same stuff as you would see in half a million quids worth of boat and of course we feel smug about all the money we are saving as we squeeze into the last tight mooring and pay less for licence and moorings.

[W+T]

9 hours ago, Bee said:

Trying to blend in the old with the new could be really difficult if you make it yourself. Obviously the original bits were made in a mould but unless you were really careful and used a kind of external mould with hardboard or something and a heck of a lot of bracing you will end up with a bit of a mess and a couple of boat ends. So far as strength is concerned  then the answer is lots of long fore and aft stringers up the sides and some good deep stringers along the bottom and long stringers under the deck. You could have a problem with twist as well if you are thinking of a long centre cockpit. Its a really interesting project but is it worth it? Our boat is 32` but 11.5` wide and we live on it for half the summer, its a bit tight but we see all the same stuff as you would see in half a million quids worth of boat and of course we feel smug about all the money we are saving as we squeeze into the last tight mooring and pay less for licence and moorings.

I have no doubt it will not be easy, i have ways to make it work as in looking good and methods of construction to make it look right etc etc. worth it yes to me. I dont want a wide beam which is the reason i bought a NB.

 

If i had half a million in stuff in the boat as much a si love a project i wouldnt be doing this lol

 

I have plans for the stringers/ribs/keel extension etc etc to give to an engineer. look good to me and i get the twist but if craned correctly that should be ok, but who knows until i chat to an engineer.