Hello and I have a Question

[Bag_of_Daggers]

Hello,

 

I have been thinking about building my own boat for a while now. I haven't settled on a design yet, but the first one will be smallish with an old-timey look to it (gaffs and bow sprits!). This is a long term kinda thing, I wasn't even considering gathering materials yet but then I saw an ad for marine grade ply at Menard's:  www.menards.com/main/building-materials/panel-products/construction-panels/sanded-plywood/c-13332.htm?criteria1_facet=AB+Marine

 

Considering all I have read about the cost of Marine grade, is this just a pipe dream?  Does anyone have experience with Product?

http://www.menards.com/main/store/20090519001/items/media/BuildingMaterials/rsbrgforest/Prod_Tech_Spec/ROS_ABMarine_PIB061412.pdf

 

 

If this is the real deal, I guess its go time. But part of me thinks it time to call shenanigans. 

 

Thanks,

Steve

[Hirilonde]

it looks like just another marinized version of AB Fir plywood.  I would never use it to build a boat.

[PAR]

Welcome to the forum. I'm not sure of your location, but in the USA you have two basic choices in low cost plywood, other than Lloyds certified BS grades. These are "Exterior" and "Marine". Both are made with the same species and WBP glues, but the marine grade is a higher quality sheet, with fewer defects, repairs and voids. This said, both are pretty poor choices, as the quality under the APA is strictly voluntary and the current trend is toward profit margins not quality sheets.

 

With careful examination of each sheet, you can pick out the best of the bunch, but this is a lot of effort, especially if buying lots of sheets. I'm not sure what you've found, as I couldn't get your PDF to open properly, but Dave is probably correct and it's just a low quality APA marine grade. This is an area where you do get what you pay for, so if the price seems good, you better look really hard at these sheets, because there's likely a reason they're cheap.

 

My data base shows Menard's selling 1/4", 3 ply AB Marine plywood for about $35 a sheet. This isn't very strong and finishes like crap. On the other hand, you can get a BS-6566 grade 1/4" sheet from Bateau, which will be 5 ply, not 3 and far better in quality and finish, for $42. Seems a pretty trivial bit of economy, if you ask me. Assuming you need say 10 sheets, you only save $70 using the AB Marine, but it's weaker, doesn't finish well and isn't as reliable as the BS-6566 sheet.

 

Simply put, considering the over all cost of a project, at the very least you should consider a quality sheet for the planking and major structural elements (bulkheads, etc.). You can use the lower grade stock on cabinets, seats and the like, but the planking is what keeps your socks dry, so . . .

[Bag_of_Daggers]

Thanks Guys! I kinda figured that was the deal but I just had to  check to make sure.I think I will go with my original long-term plan and start to buy my materials a little at a time to spread the cost out.  Now I just have to figure out were to store 4X8 sheets. I assume laying flat is better that on edge.How susceptible to temperature changes is marine grade plywood? Can you store it outside if it is tarped?

 

 

Steve

[J.E.D.]

The add says that the face plys of the plywood are Fir and North and the core plys are American softwood. Fir has pretty good rot resistance but it is a VERY course and loose grain wood. Not to mention it is very soft. The rot/water resistance makes it good for exterior apllications such as building construction. The "marine" grading like PAR outlined before just means that the faces are free from knots or fillier patches.

 

In my oponion, this material has enough water resistance to be used for boats, but it is far too soft. The grain can be literally pulled apart with you finger nail. It's practically impossible to sand it smooth enough so as to not "catch" and tear out the grain.

 

For "stich and glue" construction. It might be okay.

[PAR]

APA's marine grade standards are a little tighter than just surface defect count, compared with APA "Exterior" grade. Both Marine and Exterior have to have rot resistant species throughout the sheet, but Exterior can use different species, while marine is a consistent species (Douglas fir or Western larch). Internally there are also differences in defects, void count and width, veneer spacing/count, etc.

 

We're in agreement that both the Exterior and Marine grades by the APA aren't really suitable if you want something easy to finish, even with taped seam builds. I do use a fair bit of this stuff, but it's usually hidden inside transoms, as soles under textured finishes, countertops, rough furniture and cabinet boxes, etc. I've used it sporadically in bulkheads and furniture partitions, but again only is covered or out of sight. I've done a number of Formica and veneer covered bulkheads using this stuff, successfully. I generally don't use it in the bilge, as the WBP rating is accurate, I just don't trust it any more.

[J.E.D.]

Very well said, PAR. You know your business better than I.

[Charlie Jones]

A point I'd like to add. I beat this "use quality wood" drum all the time.

 

A few years ago I built a 22 foot sailboat for a customer- all up, it cost him about 22 grand, sails, etc included.

 

I priced the plywood materials using Fir Marine, and again using BS 1088 quality stuff.

 

The cost difference for the entire boat, would have been $700 which is a ridiculously small amount to try to save in  a $20 K plus overall expenditure.

 

And the bad taste from using cheap stuff lingers forever.

Use the BEST materials you can get- Your TIME is worth so much more than the wood is, and you can Never regain that time.

[Frank Hagan]

The cost difference for the entire boat, would have been $700 which is a ridiculously small amount to try to save in  a $20 K plus overall expenditure.

 

It is one of the first expenditures a new boat builder considers, so the cost of ply may take on an overstated importance.

 

In my case, I never expected my boat to last more than five years, and I considered using the cheapest materials a challenge. It's 13 years later and the boat, still living on her trailer but now at a nephew's house, is doing fine. I used construction grade lumber and exterior ply, the cheapest epoxy I could find, and marine salvage materials where possible. HOWEVER, had I known someone else in the family would want it, I would have used better materials. There's a lot of maintenance that starts to become necessary after a few years.

 

If I were to build another boat, it would be a better design and I would use much better quality materials.

[PAR]

On traditionally constructed craft, the best lumber in the boat is usually the planking. The reasons should be obvious. With modern techniques, materials and most importantly attitudes toward maintenance, the same should be true about the planking, if not more so, considering the generally lower level of routine maintenance it will see.