Knowing one khaya species from the next

[iwally]

First - I also posted this question on Danenberg's site, please let me know if this is a faux pas in this small boat community.

I've decided that my best bet is to go with African mahogany - khaya ivorensis - for replanking and frame work.

Reportedly some species of khaya (ivorensis & anthotheca) are very good to work with while others (negra and rubra) are pretty bad to work with. The only mention of anthotheca I've seen was on this forum; haven't seen anything about khaya senegalensis.

So how do you assure yourself that you are buying the right species? That is - at the lumberyard how do you know one from another; or can you? Other than whatever label the distributor puts on it.

[Peter M Jardine]

This is a really good question.... with not any fantabulous easy answer. The word 'Mahogany' is probably the most misused word in the wood species vocabulary. You can still go into a big box builder store and have the various brown softwoods from the Asia Pacific rim area referred to as ' mahogany', when nothing could be further from the truth. I must admit that my understanding of mahogany was based in the sixties and seventies, when almost every lumberyard still had a pretty good chance of getting real mahogany, or something close to it. It took me some time and a lot of questions with really knowledgeable wood folk to get to where I am now, which is hardly more than an informed amateur.

The two species of Meliaceae which are mentioned here, are one of seven species that are considered real mahogany, besides the Swietania variety, which we refer to as 'Honduras' mahogany quite commonly. One of the ways of identifying Khaya species is by density, which is generally harder in two of the most common species, which are Ivorensis, and Senegalis. Most of the Khaya species grow in rain forests which have longer dry periods than most. The result is denser harder wood that machines well, and in larger trees exhibits good grain characteristics for boatbuilding. All of the seven species are now considered vulnerable, as demand strips the old growth rainforests at an ever rapid rate. It is very difficult to absolutely identify an exact species, but better yards look fairly carefully at the area the lumber is coming from as a general precaution. Bottom line: You can still buy some mighty fine khaya for reasonable prices. The down side of Khaya is that it is not particularly steambox friendly compared to the Shorea family, or even the Swietania family, but this is somewhat anecdotal and personal experience for me. I personally think that Khaya is the best most cost effective material to use these days. You can still buy Swietania Macrophylla, but it's expensive. I have bought some absolutely stunning Khaya from 6 to 9 dollars Cdn a board foot.

One thing is sure, Chris Craft used a variety of species to build their boats. These included a lot of the Shorea family, widely called Phillipine mahogany, or Meranti, but in fact it's not a mahogany at all, but an unrelated hardwood. This family still provides very good boatbuilding wood, but various specific members are more resistant to rot, or have better runout or grain characteristics. One military officer I communicated with, who had significant time in Phillipines and areas around, told me that Tanguille, or Shorea Polysperma, was one of the most harvested woods in the 50's and 60's. It is no longer cut or exported from the Phillipines, mostly because there isn't any left. Within the Shorea family, density varies fairly widely. I know that the planking on Vanora (1964 Challenger) was quite a bit lighter than the replacement Khaya.

It's fair to mention that there is some good mahogany of the Swietania family coming out of Peru, but most of it is apparently harvested illegally. There may be some sneaking out of Brazil too, but they banned exports over a decade ago.

One of the key points to remember is that almost all the wood that CC bought all those many years ago came from long established old growth forests. These trees were massive old giants of the rainforest, and we will not see their like again. Whatever species they were, these forests were the best of their kind. It's hard to compare some of that wood to what is available today.

[iamallthumbs]

Anyone else watch "This Old House" on PBS last week? They are rebuilding New Jersey shore houses and the porch on one house was being covered with mahogany because as the builder said, "it is straight and resists rot". No idea what species of mahogany they were using but the wood looked pretty nice. If, in fact, it was high quality mahogany being used for a porch, I can understand why it is expensive to purchase such wood for a boat rebuild.