21 replies to this topic

[RC Bill]

I'd like to put some plywood on order for my Spindrift 10 so I just need 4 pieces.  According to the ad, "Hydrotech" Meranti /Keruing Mahogany  is a marine plywood, engineered to BS1088 standards.  The cost is about half what I'm seeing for the more traditional marine plywood.  Though even at that, it is still about $98. per piece shipped for 1/4" (6 mm).  I punched the name in the 'messing-about' search field but nothing came up.

 

If you have any history with this material, can you please post?

 

Thanks,

Bill

[PAR]

I've used Hydrotech a lot over the years, as well as Aquatech, wqhich is a BS-6566 sheet and it's good stuff. I can get 1/4" Hydrotech for about $50 a sheet, plus shipping. If you'd like I have a supplier for Hydrotech (and Aquatech) that will charge about $150 to ship to you, if you're willing to pick it up at a distrubution center. If you provide your address (email me) I can get an acurate quote. Naturally, the more plywood you buy, the lower the per sheet costs after shipping.

 

Hydrotech isn't as good as Joubert BS-1088, but this is usually Okoume, which is lighter, not as strong and not as rot resistant either. A Joubert 1/4" BS-1088 sheet (Okoume) is $85 at my supplier, plus shipping.

 

The short of it is, shop around, as these specialty plywoods (marine grade is a speciality grade) can get priced all over the place.

[Howard]

Bill:

 

I don't have any direct experience with Hydrotek (the Meranti stuff), but I'm about to. Just unloaded a ton of it this morning.

 

Two issues with using it on the Spindrift, vs. the Okoume. One is the additional weight (about 20% greater per sheet) and the other is the ability of Meranti to take that tortured curve in the bow section. If the weight is not going to be an issue, give it a try. It is one of the plywoods listed on the plans. Also, if you plan to finish it bright, it will come out darker than Okoume.

 

One other item that often pops up when you start looking at these exotic plywoods is the notion that Okoume is not "durable". Once you encapsulate it in epoxy, that issues goes away.

[Pete Brigaitis]

I used Hydrotek on my CS 20. It is indeed a bit heavier and does not bend quite as well as okoume, but it is very resistant to rot and delamination. I left several scraps out in a bin for over a year They went through multiple soakings and freeze/thaw cycles and long stretches of time in moist hot conditions and are still in pretty good shape. Worth the added weight in my opinion.

[Regan Magor]

Hi, I'm new here... I was going to do one of those introductory posts that people do but this is a topic that I had questions about, too, so I didn't want to miss out on the discourse. I don't want to hijack your thread, RC Bill, so hopefully I'm asking something you meant to ask but just didn't get around to yet.

I have plans for a CS20 (#157) and the cost-savings of using Meranti ply compared to Okoume seems pretty compelling. Is the extra weight of the material significant enough to make a huge difference in performance considering no astonishing acts of racing or heroism are planned to be taking place on my boat.

Being a bit of an idiot when it comes to damaging things, I don't want to take chances with the hull's integrity by not fibre-glassing the entire thing. Because, seriously, I don't cover every square inch of the exterior with fibreglass, it'll look like a slice of of Swiss cheese by the end of its maiden voyage. That said, I plan to glass the hull... From what people say about the weight and durability of Okoume, it makes a lot of sense to glass your hull; from what people say about the durability, weight, and rot resistance of Meranti, it could be a bit much. Is it overkill, when using Meranti, to glass to that extent?

How does it look with a bright finish? If you have a wooden boat,there should appear to be some wood comprising said boat. My plan is to go bright with the deck and, likely, some of the interior. Is Meranti attractive enough to dress up pretty like that?

Thanks for your help and sorry if I wrecked your thread, Bill!

[RC Bill]

No problem, Regan.  The more questions and answers we get in here, the more we all learn.  Thanks all for the input on the Hydrotech.  I hadn't thought much about the weight, which should be a factor for me since I plan on car-topping the Spindrift, but I don't think another 10 or so pounds will matter too much.  I can get it for $43./sheet/6mm plus shipping which is quite a savings over Okoume.  I'm worried about the bow bend but will take it slow.  If Howard, with all his experience, is using it for his build, it'll be fine for the Spindrift.

 

I found a thread on the Wooden boat forum discussing the weight and the following site give weights for most of the common boat building plywood, http://www.noahsmari...ywoods-can.html

 

Thanks,

Bill

[Scott Dunsworth]

I prefer Meranti, not because of the lower price. It is so much harder and resists dings much better, you don't have to be as careful sanding, the okoume will if your not very careful sand high and low places. When your sanding screw holes you have to be extra careful not to tilt the sander on edge or you will end up with a lot of divots with Okoume.

If meranti was more expensive it would still be my choice.

I built a spindrift 10n with it and it is stiff for the bow section but I did not have and issues with a little preparation.

If your concerned about weight, you could use Meranti for the bottom sections and Okoume for the top sides. That's a happy medium of weight, cost and durability.

 

Every sheet of ply I have bought has come from noahs, doing boat number six now.

[PAR]

There's a huge difference between the colors of Okoume and meranti. Okoume is very light, often with a slightly pinkish tint, while meranti looks much like mahogany (often called Philippine mahogany) and is quite dark. Meranti is stronger, stiffer, harder and more durable than Okoume.

[Regan Magor]

It sounds a lot like the choice comes down to personal preference. As I said, I'm a klutz, so I'm likely to go with the strongest option. Thanks for the input up to this point. I'd like to hear more about personal experiences re the pros and cons of Meranti, generally.

[Terry Dunn]

RC Bill,

Eleven years ago I built my S10 out of cheap fir plywoood from a big box store. Real tough to bend.  I did not have a clue what I was doing. Since it was fir I encapsulated in FG. This was my practice boat. I was not smart enough to figure out ahead of time that it may be cheaper to build with good marine plywood than spend the money on FG and expoxy. My S10 weighs over 130 lbs so she sits on a trailer.

 

The following year I built my CS20 out of 6 MM okoume and 3/8" marine fir. So much easier to work with the okoume.

 

I still have both boats sitting on trailers next to the house. The S10 is fun to take to the  lake for the grandkids to row around.

 

My CS20 is finished bright because I was to lazy to paint. Just slapped on some Marine spar urethane. The S10 is painted.

 

I have seen a boat built with meranti finished bright and I think I like the looks of the meranti better than the okoume. Always a case of personal preference.

 

Good to hear you are planning on quality plywood. I look forward to seeing pictures of your build.

[Dale Niemann]

I built my "Lively" CS 17  almost 5 years ago now and used Okoume exclusively for the plywood.  I varnished the decks and painted the topsides and interior with system Three.  I did not fiberglass anything except the seams.  It has held up very well.  There are a few dings on the topsides but no other problems.  However, I did cover the small exterior keel with xynole and it has served me well because I frequently pull the boat up on sand beaches.  I also did add a 4 " strip strip of xynole on bottom outboard next to chine.  It was designed to protect the boat as she leans to one side or the other and it has done just that. By doing this I saved a lot of weight.

 

Look at the photo gallery on our West Coast Trailer Sailing Squadron and you can see photos of Lively or the many post I have here.

 

http://members.ij.net/wctss/wctss/

[Howard]

These are some samples of 3/4 inch marine fir, meranti and okoume:

 

 

A few things you notice are the number of plys.........7 for the fir, even though it is marine grade.......13 for the other two. Even though the fir was marine grade, it has a number of voids in the plys and checks checks in the faces. In one instance, I counted 13 footballs in one 2' x 4' section. That was for fir from 10 years ago. The current stuff is much worse.

 

The meranti and okoume have not had the issue with voids.....or at least the stuff I have used in the past have not. An interesting thing happened with this sample of okoume..........again, it is 3/4 inch and appears to have been made by glueing up two 3/8' panels. Not what you would expect to see. Bottom line is with the declining quality of everything, there are no iron clad assurances of anything. Others may chime in, but a good indication of quality may be the price. If something looks too good to be true, it probably is.........and that may mean some cheap, inferior stuff that is not what you thought you were getting.

 

Second photo is of the same pieces of plywood........these had some oil applied to give an indication of the color if finished bright:

 

 

Again, from left to right........fir, meranti and okoume. I don't think the normal meranti will finish as dark as this appears. It is lighter than walnut.  Okoume does seem to have a pinkish tint to it.

[Howard]

BTW, for the boat I'm about to start on, I'm using meranti for everything below the sheer, and okoume for everything above (cabin top and sides).

 

Not to throw a monkey wrench into the works, but the supplier I ordered from mentioned that the Hydrotek they ship can be either Meranti or Keruing, the latter being even harder and heavier than Meranti. Pot luck with them what you get, but it all comes to them marked as Hydrotek. I suppose most suppliers have the same issue.

 

That might be a blessing........or not so much, depending on what you were going to do with it. For some uses, you can get too much of a good thing (stiffness and weight).

[RC Bill]

I built a spindrift 10n with it and it is stiff for the bow section but I did not have and issues with a little preparation.

If your concerned about weight, you could use Meranti for the bottom sections and Okoume for the top sides. That's a happy medium of weight, cost and durability.

 

Every sheet of ply I have bought has come from noahs, doing boat number six now.

 

I decided to follow Scott's suggestion and ordered two sheet each of Meranti & Okoume so I can have the toughness and the weight saving as far as possible.  I also decided to order from Noah's.

 

This has been a really interesting and educational thread.

 

thanks,

Bill

[PAR]

For single chine boats like this, a lot could be said for a meranti bottom, with okoume topside planking.

[hargrave]

I built a Pooduck with meranti. The strakes are 3/8(forget the mm) and the garboard has a lot of curve to it up in the bow. It took some convincing, but it did not crack and held it's shape well. I would definitely use meranti again- unless I win the lotto and can afford sapele.

One thing; meranti demands a sharp, sharp new blade, whether on the bandsaw, skil saw, jig saw or table saw. Bosch makes some great jig saw blades that reduce tearout on both sides. Meranti splinters a lot. Wear gloves.

[Regan Magor]

What's the general feeling on glassing the hull? Is it over-kill if you're building with Meranti? Is it over-kill in most circumstances?

Dale, you didn't glass Lively and she looks awesome. Is there extra maintenance involved in keeping sound a boat that's only protected by epoxy and paint?

[Hirilonde]

My Spindrift is Okoume, epoxy and paint and I...........

 

*drag it up onto the dock

*drag it up onto the beach

*slide it into the back of my pick up truck

*haul it up into the loft of my garage

 

I find the key is to put a metal (bronze in my case) chafe strip along the length of the keel and make it a practice to drag it level on the keel.  Yes, fiberglass, or other cloth and resin will make the bottom more abrasion resistant.  But with care it isn't needed in my opinion.  And I really, really, really like a light weight boat.  It sails faster and is easier to move around.  But this is just another design criteria that has compromises and you have to pick the ones that suit you best.

[Regan Magor]

You're beginning to assuage my paranoia... Maybe even a klutz like me can live without glass. I wish these decision were easy. Then I'd be able to spend my time thinking of other things instead of only about building a boat all the time, every second I'm awake.

[PAR]

Training wheels on the corners of the transom don't weigh much and could eliminate much of the dragging around concerns.