|
Post by Admin on May 18, 2020 12:18:33 GMT
The laminate Matrix varies depending on the type and thickness of ply used on each. Do it once and do it right as per the list in Builders notes. It is very specific and must be followed. You must declare everything on your Class Registration form that can now be downloaded from the 5.80 website. Good luck!!
|
|
|
Post by Admin on May 27, 2020 12:19:05 GMT
I have had two different people ask about the possibility, when two complete layers of Epoxy Glass is required on the hull because of weaker Ply..if they can coat one layer on each side of the plywood (making a stronger core structure and stiffer). instead of two layers on the outer skin...they would do that by laminating one side of the plywood sheet before cutting and planking on hull...this then is the inside of the hull so it is then glued and screwed to the frames and stringers and then the outside seams are glasses and one full glass on the whole hull. . YOU MUST NOT do this..
Here is the comment from Janusz....I Absolutely do not recommend laminating plywood on both sides. Solid wood also cannot be completely encased in a laminate. I am well aware that such a solution has been promoted since the eighties. I have many observations. Always bad. It doesn't matter if mahogany, red cedar, balsa or other species were laminated. Boats built in this way are not durable. It is enough that a small amount of moisture gets inside and the wood rots very quickly. You can build a kayak or other small boat that only sometimes goes on the water. Durable constructions are plywood yachts laminated only from the outside and only with epoxy resin.
|
|
|
Post by crewzing on May 27, 2020 12:56:30 GMT
Interesting, I’ve built a number of composite boats over the years as a professional, most having a combination of both wood and plywood and this is the 1st I’ve heard that ply should only be laminated on one side, especially if it’s supposed to weaken the structure and promote wood rot 🤔
|
|
pete
Junior Member
Posts: 56
|
Post by pete on May 28, 2020 7:38:30 GMT
Understood about exterior lamination only - if thats what is defined by the NA thats fine by me, however we've obviously got to seal the interior of the boat as well from condensation and bilge water etc, even if this is just a saturation epoxy coat (no glass) i guess? Does this differ in some way from glassing it in terms of reducing rot possibilities? (note - i've made and maintained a variety of boaty stuff, but never a full plywood hull before, so I am in no way an expert. Be gentle!)
|
|
|
Post by Admin on May 28, 2020 9:03:56 GMT
YES you definitely need to seal ALL interior timber sufaces and there are various options, from timber primer and then marine paint , or epoxy sealing, or Varnish and oiling for dressing certain timber parts. Marine ply will have an outer veneer that should look pretty cool! so on Trekka 01 we will be using that to create a warm interior with varnished timber bulkheads and bunk risers, a little timber capping, but white painted Hull and deck head...then with Sunbella type upholstey it should look OK..we also intend to have a galley with sink and pump and Chart table opposite...cetainly every part of the hull and deck under the cocpit etc will be completly timber sealed forever...so with a bit of sensible maintinance, she should last 50 years or more.
|
|
martellmarine
Junior Member
Husband & wife team building boat #71.
Posts: 61
|
Post by martellmarine on May 29, 2020 5:04:34 GMT
Just curious, If someone puts the required laminate on the exterior of the hull as per class spec, AND then decides to put some more laminate, say a 200g boat clothe on the inside bottom and lower panels as well, then that should be fine, correct? Janusz' comment is a personal recommendation only, not a requirement, is this correct?
|
|
|
Post by Admin on May 29, 2020 10:53:38 GMT
Yes that is correct...so the compulsary requirement is the two layes outside.( if you have that ply) that is all....with everything it starts from the structural spec on the plans..that is a must and you are NOT able to reduce or weaken anything...you can modify the companionway..deck layouts , galley and Chart table but the rest must be built as designed as a MINIMUM..so if you decide to strengthen some parts you may....but the design is VERY STRONG!!...in my case as an example on TREKKA Hull 01 I will put an extra layer of Glass where the keel bolts on and about 10cm around the base plate...I just know over the next 20 years or 40 years with the keel coming on and off, we may sand it down to clean off that area and would rather have two laminations than one?? to allow fo some sanding back. I am also thinking of one extra layer of glass around the bow area and a little up the stem, not far and back about 30cm just to increase UFO impact restitance ...so..you can do little things but don't let your 5.80 get too heavy ..it is your dream boat and you can pesonalise it? TREKKA will sail the Mini Globe Race by someone?? so...good luck!!
|
|
|
Post by renaud on May 30, 2020 6:10:49 GMT
regarding the laminating 1000 gr of fiberglass roving is not easy to finish (sanding + filling) and difficult to find. Will multi-laywer (600+400) (300+300+400) can be accepted?
|
|
|
Post by Admin on May 30, 2020 9:31:47 GMT
Hi...You will need to show it repesents no less than the original specification...with comparison data....we do not do that...that is your responsibility ..and then document the process clearly on your Builders blog..Include all when you submit your Class Registration....but sounds ok...THNX.
|
|
martellmarine
Junior Member
Husband & wife team building boat #71.
Posts: 61
|
Post by martellmarine on Jun 6, 2020 6:10:23 GMT
regarding the laminating 1000 gr of fiberglass roving is not easy to finish (sanding + filling) and difficult to find. Will multi-laywer (600+400) (300+300+400) can be accepted? You must be one of the few who are able to get 10mm ply...?
|
|
|
Post by renaud on Jun 6, 2020 6:31:06 GMT
I am trying to choose what will be the best for me (as per my knowledge).... okoume 9mm with hugh amount of fiberglass and lots of work okoume 10mm a bit better.... or Mahoghany 10mm require 200gr fiberglass - but product is a lot more expensive...
|
|
|
Post by grants on Jun 6, 2020 9:35:50 GMT
Hi, Quick Question. I know you mentioned at some stage the possibility of using Flax Fibre instead of glass fibre. Is this still a possibility for approval to spec? (using standard epoxy resin)
|
|
|
Post by Admin on Jun 6, 2020 9:56:09 GMT
We had one builder doing the research for us to confirm engineering and spec but as yet no answers...when we have it we will decide and let everyone know..it is more expensive but eco friendly...NOT approved for now till we do the numbers..as long as it is same strenght we will approve it...THNKS
|
|
martellmarine
Junior Member
Husband & wife team building boat #71.
Posts: 61
|
Post by martellmarine on Jun 6, 2020 10:52:28 GMT
I am trying to choose what will be the best for me (as per my knowledge).... okoume 9mm with hugh amount of fiberglass and lots of work okoume 10mm a bit better.... or Mahoghany 10mm require 200gr fiberglass - but product is a lot more expensive... Would you say that you have a lot of fibreglassing experience? If not, 1170g is quite the handful for a first time layup. Applying a single layer 200g clothe is a much easier exercise. Do you intend to sail around the bay or get involved with extended ocean voyaging? The bumps and knocks of local day sailing or weekend cruising verses the rigours of extended offshore cruising/racing can be quite different. 200g is actually quite a light weight sheathing. Properly applied it is a perfectly adequate waterproofing membrane but potentially quite susceptible to lighter bumps and knocks. More glass can enhance both abrasion resistance and structural integrity. My personal choice for a plywood offshore racing/cruising sailboat would be to have more than 200g of glass on it, especially below the waterline.
|
|
|
Post by jaysen on Jun 6, 2020 14:44:16 GMT
I am trying to choose what will be the best for me (as per my knowledge).... okoume 9mm with hugh amount of fiberglass and lots of work okoume 10mm a bit better.... or Mahoghany 10mm require 200gr fiberglass - but product is a lot more expensive... Go for the middle... 9mm non-oakum with the medium glass requirement (2x600g). This will give you the strength of the stiffer wood with the protection of 1200g glass layup. Keep in mind we can use multiple layers of lighter glass to hit the target glass spec UNLESS it is specified as a single layer (such as in the taping of the below water line chines). For example, to get an easier to fair final layer, you could to a 600/400/200 layup (ensure green at minimum) and get a very nice base with very low weave to fill. Take what martellmarine said to heart though too... build to suit your intended use. No need to build a tank if you aren't doing battle in the sea
|
|