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I am building the 19' barrelback, Hankenson design and am wondering why they dont advise the use of white oak for the frames. I have use it many times in the past for boat frames, wondering why not on this one!

Flyer

You can use white oak. It is much heavier than Mahogany. It bends better. There is some question of white oak saltwater and epoxy. Mahogany is lighter, almost as strong and is fairly rot resistant. Mahogany is easier to work with, to me.

Bill

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Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
Tahoe 19 Build

Aren't there some problems with epoxy sticking to it also in that you have to make sure the surfaces are roughed up more?

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Boat building can best be defined as an endless series of
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Don't Dream Your Life, Live Your Dream

I would think that epoxy would bond to the oak even better given the pores and the fact that it doesnt have a natural oil in it like mahogany. I am going to use it, it is local and vailable and is tryed and proven for many, many years.

Douglas Fir or Mahogany are suggested as suitable wood species in the Hull Material Listing section of the Barrelback 19 Bill of Materials, but other alternatives are listed in the Lumber & Plywood section :

Quote:
Lumber typical to the locale and proven in use in boats of similar type can be used as long as the weight, strengths, and characteristics are similar. Suitable boatbuilding woods include white oak, mahogany (Mahog.- Philippine dark red, American, or African types commonly used in boats), Sitka spruce (SSP), Alaskan cedar, Port Orford cedar, Douglas-fir (DF), longleaf yellow pine, apitong, and teak.

Source : Barrelback 19 Bill of Materials

If using white oak, follow the surface prep recommendations in the Epoxy Technical Manual. Other epoxy brands will recommend similar guidelines :

Quote:
WHITE OAK: A slightly roughened surface (such as that resulting from bandsawing) may be preferable to planed, smoothed surfaces. Being a porous wood, care should be taken to prevent "glue-starved" joints. Using POXY-SHIELD®, apply a thin coat to mating surfaces and let cure without joining. lf obvious dry spots recur, apply another thin coat until the wood is sealed. Then glue in normal manner, avoiding excessive clamping pressure. lf joint is under bending stress, keep clamps in position until complete cure takes place.

lf in doubt about adequate bonds, or your tests indicate a potential weakness on a wood not mentioned here, give the mating surfaces a solvent wipe first, such as with acetone or lacquer thinner; this is particularly effective with hard, dense hardwoods, or those with resinous or oily characteristics.

Source : Epoxy Technical Manual - Surface Preparation

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Paul Kane
Kane Custom Boats Ltd.
Chelsea, Quebec

Building the Glen-L Hot Rod : http://www.kanecustomboats.com

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I am hoping soon to build my Key Largo (utility style Barrelback) and have looked long and hard at what wood to use for the structure. I settled on african mahogany (Khaya) for this, it is lighter than white oak. Ken Hankinson specifically stated in his instructions to avoid using oak. White oak adds extra weight that will negatively affect the way the boat performs. African mahogany weighs about 3.2 lbs per board foot and douglas fir weigh about 2.7 lbs per board foot, but white oak weighs about 4.2 lbs per board foot. That means the oak boat structure will weigh roughly 30% more than with african mahogany and roughly 50% more than with douglas fir. That doesn't mean the entire boat will be 30% heavier, but it could translate to my guess about 10% heavier overall. That is in my opinion an overweight boat. More weight means more engine power needed to get on plane and reach your desired speeds. It also means higher operating costs too. I recommend staying with the recommended douglas fir or african mahogany for building the boat's structure. For the Key Largo I estimated it should weigh overall about 2000 lbs for the 19 foot version and about 2200 lbs for the 20 foot version, so you can see that an extra 10% weight increase amounts to 200 to 220 lbs more boat to push around.

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Griffin's Law: Murphy was an optimist.

PeterG

Many designs use Mahogany or DF for frames and white oak for shear, chines and keel. Don't use red oak.

Bill

_________________
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
Tahoe 19 Build

I used all Doug Fir for frames battons Ect. Only problem I have had is the side frames can't take a hit from a Waverunner at 40MPH without braking !

I think peter G's logic is in the right place but slightly flawed. I have calculated the BF needed for frames and it is far less than 10% of the boats weight. Just to order rectangles to encompass every frame member of the barrelback 19, the total BF is 55 in 4/4 lumber. Planed to 3/4 thickness and estimating 10% loss (very conservative) cutting out to actual parts, the final total BF 37.125. If you use data from http://www.csudh.edu/oliver/chemdata/woods.htm to find the density and then convert BF to cubic feet, the weight of the frames alone (no ply, no glue, just wood) in pounds are as follows:
White Oak 138.0984105501
Mahogany 129.905339949
Ash 124.0798486851
VG Douglas Fir 99.5629416012

Clearly White oak is heaviest, but total change in weight for the boat i 39lbs from the lightest (doug fir) to the heaviest. Between mahogany and white oak it is 8 lbs.

Yes. In the big picture the frames cost/weight are nothing.

Bill

_________________
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
Tahoe 19 Build

Heres the deal on White Oak. there is 2 things.:
W Oak is so dense that epoxy does not have a chance to penetrate very deeply into the grain, therefore the glue bond is shallow in the grain structure.

White Oak expandes greatly when it sees moisture. I know of no other wood as unstable as far as moisture (water) is concerned. The epoxy glue line IS stable in the presense of water (moisture), therefore in the presense of moisture the W Oak will expand against the non-expanding glue line. When this gets repeated over time the oak can break the glue line.

Salt water is BS concerning White Oak, it is simply water of any kind that makes Oak swell up. This wasnt a issue in the days of oak bolted together with mechanical fasteners, and older glues. The newer glue (epoxy) is when this issue come to light.

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Just to throw my 2 cents in...
Over the past 25 years, I have used white oak and west system epoxy in the rebuilds of two 27' Friendship Sloops and many small sailing craft (less than 16') and have used it to frame my current 23' Tahoe project and have never had a failure.
As to using white oak for framing, if you choose to do so, make sure that it is dry. When laminating my stem I had used white oak that was still too green. Fortunately, the assembly sat for a number of months before I was ready to mount it on the frame, In that time the white oak warped and tore apart the plies in the plywood.
Good luck with your project!