composition of luan(and glass)

Im sure this has been asked numerous times before but bear with me.what wood is every day home depo luan composed of.i am looking to use it as a cheap core.will have woven roving and chopped strand on both sides.the idea is cut it into strips and cover the patterns i have made for a hull then sandwitch 1 ox mat inbetween the next layer of strips of luan to ensure good bond.then remove all faseners and cover in multiple layers of biax or roving on inside and outside using us composits 635 epoxy resin.i figure it will be hard to pierce the thick roving and even if it happened the second layer of luan would remain dry due to the layer of matt between the luan strips.this would make repair easier.I have rebuilt many boats and have the erge to try one of my own design :the dorado bottom profile with a carolina appearance.I dont know how its going to turn out so im trying to keep cost low.If it works satisfactory i will build another.Any help would be appreciated .I gave up on getting plans so im just going to wing it.

 

Sounds like you're building a one off 'glass boat, using a single skin method over a male mold, but you're adding a few extra steps in technique and materials that will only increase the costs and labor needed.

Typically, temporary station molds are set up on a strong back, over which is sprung low grade lumber. This is covered with plastic drop cloth material or similar and then the mat/cloth set in goo is applied. This stuff (luan) is pretty flimzy so your station forms will need be closely spaced to prevent the stock from sagging under the weight of itself and the 'glass work. This is why most plans, intended for the backyard builder, suggest using furring strips instead, because they will not sag if your forms are on say 36" centers (1/4" Luan will at 36")

Once cured and faired, the hull is popped off it's form (male mold) and the mold is tossed in the fire pit or used in other projects, like template and pattern making.

I suppose you could make the luan part of the structure, but it's not very strong, has little resistance to moisture and will not add much to the structure.

The stuff you see at LowesDepot, commonly called Philippine mahogany or Luan is really a pine and not anything to get excited about. The construction is poor, outer skins very thin and generally only good for paneling your den. The use you have in mind is a good one for this material as it will serve as the form, which you can layup a 'glass schedule. I use the 1/4" and 1/8" stuff for templates all the time as it's cheap and I don't feel bad about screwing up a cut or two on a piece. My pattern making stock usually is 3 to 4" slices that I rip from the sheet on the table saw and tack or hot glue together as needed.

 

mold?

I just thought the luan would space the glass further apart and therefore add stiffness.I just finished some work on a pacemaker with nidacore and wasnt very impressed.I dont know anything about vaccume bagging so i just applied thr resin over matt and woven.the finished product was strong but heavy.Also they dont recomend use below the waterline so i came up with the luan idea.what other materials are suitable for a project such as this?

 

Not knowing what you're trying to do, prevents me from providing much more . . .

 

Building A Boat

Im Trying To Build A One Off Hull That Is Strong And Low Maintence That Doesnt Weigh A Ton But Doesnt Have To Be A Featherweight Either.there Are No Kit Boats Or Plans Of A 35 To 40 Carolina Boat Available So I Will Reverse Engineer One To The Best Of My Ability.from 2 Specific Boats In A Local Boatyard.i Posted Some Picts Of Boats I Have Renivated And Altered In Fiberglass Hulls.these Projects Were Too Much Work Trying To Make Somthing Out Of Them That They Were Not Intended For.so This Time I Want To Start From Scratch.i Just Got Bit By The Boat Bug And Cant Stop.i Even Had A Large Climate Controled Structure Built To House My Boat Addiction.i Guess I Could By A Hull And Start There But Wheres The Fun In That.i Spend Hours Daily Working On My Projects And Will Go Back To College To Study Design And Theory Of Hulls Etc If Nessary To Make This Dream A Reality. Anyway Thats What Im Trying To Do.

 

Designing a vessel of that size (if I understand you correctly a 25' power boat) would require a whole lot more then reverse engineering a couple of similar designs. In fact, reverse engineering anything requires much more engineering and understanding of the concepts and issues involved then a new custom design.

There is a great deal of study necessary for even the smallest of craft to be reasonably successful (insuring it will float right side up is a good start) I'd strongly recommend you bone up on the education end before plunking down hard won money in a speculative engineering project, where as the issues, mathematics, physics, and hydrodynamic concepts aren't well comprehended. Going farther from shore then you can swim back to in a craft of unknown or understood stability (as an example) is foolish.

 

thanks

it time to sign up for classes in south hampton college.

 

There are two kinds of luan ply,exterior glue and the other.Very few places around here carry the exterior glue type,the only type you would use in boat construction.I only use it for bow caps and consoles and trim,I don't know about below-water applications,even the exterior glue type is pretty cheap stuff.I've never seen it in the Depot or Lowes.

 

ply

with ply what thickness should be used to cold mold a hull.i wanted to use 3/8 if luan wouldent work.2 layers on sides four on bottom covered with 2 layers of 18oz woven.Do you recomend a layer of matt between layers for adhesion?

 

You can use akume or meranti (I know spelling is wrong) they are mahogany. Exterior 1/4in luan has 3 layers while the other two have 5 to seven layers (plys). Meranti even has the loyds of londons stamped on it for boat building. BUT it is also 35 dollars and up a sheet while luan is around 8 dollars a sheet. I do know of 3 cold molded boats that are around 10 years old that used luan. They are going strong. However they may have used better material then to make it. I didnt know that luan now was made with white pine.
Thickness 28 foot and down I would use two layers of 1/4 inch for the sides the bottom we use one 1/2 inch layer and 3/8 inch layer. Also the bottom is done with AC fir.(the best we have around here to use, there is better out there though
Good luck
Ben

 

Carolina Sportfisherman boats have laminated plywood bottoms. If you use epoxy there is no need to add anything. You can make a core of wood. Cold mold the boat and fiberglass over. There are several scantling rules that work fine. Dave Gerr's book has easy to follow formulas.

 

now the design

Thanks For All The Help With The Materials And Required Reading.the Hull Im Looking To Build Is Similar To The Vietnam Riverine Boat 36 Ft Or To The Dorado 40(AS FAR AS BOTTOM DESIGN).what Company Sells Plans Similar.if They Are Not Exactly What I Want I Could Always Change The Cosmetics.i Would Like To Give It That Distingushed Carolina Look.

 

I build canoes out of $8 dollar luan all the time. I have one that is 3 years old made of 1/4 inch luan. The label specificaly says not for wet end use but I guess the epoxy takes care of it. This canoe has fallen off my jeep and been ramed at speed on several large rocks when trying to shoot rapids and it has not ever showed signs of failing. Although I guess stress on a smaller boat is alot less than the size you are talking about. Since you are going to be spending alot of time and money on a project this size, you might want to spring for the okume or merati. Not only does it have more layers and better faces, it looks really good finished bright, the luan doesn't. I rarely use it because it isn't available in my area and the shipping is outrageous.

 

Like you say, a luan canoe (I have one too) does not need to be nearly as strong as a power boat that planes. We have even built a canoe from the blue insulation foam you buy as home depot - it showed signs of delamination after a little use. I have abused my luan canoe and its fine, I expect it to last for a long time - but I would never build anything that had an engine out of it.

Joel

 

I'm going to jump in here and make some comments on using luan . I have been a carpenter for the better part of 25 years and there are different grades of luan.
One above had stated phillipine mahogany and it is only on the veneered surface
the rest is cored with pine but it is used for subflooring and (Core Void) clear.
The good stuff actually has fiber strand run through it vertically and is very very strong . When faced with the same ?'s as to use it for a core material in cold mold
format in small boats .... for building kayaks ,canoes, Small skiffs and row boats or small fishing boat up to maybe 18' limited to small power And a full encapsulation of fiber. Yes . it is inexpensive and very very stong.
I tried an experiment on bending properties both dry and wet ...Dry is very hard to bend on complex curves but exellent on long sweeping curves.
Wet did not offer a significant difference after a 24 hour soak, But I did discover NO delamination or warpage after completely dry and it has a memory to beat all hell.
(Hence a flat Floor for its intended use and the fiber strand) This stuff is intended to suffer abuse.Constant walk trail under vinyl. tile..etc. You all get the Point...
It has its use here . But as far as The carolina design . Spend your money wisely !!
some times that does not mean Cheap ! Good luck