African Mahogany versus Utile versus Iroko

[ErikBenson]

My 1953 Fast Motor boat- "skimming dish" will need some rotten top planking replaced. I have a supply of Utile ( 'Sipo' in French) available nearby - ( SW France). I have already used it for the floorboards, but don't know if it could replace the mahogany ( 'acajou' in French). There is also Iroko and Sapele in this suppliers. . .which one should I use and why ? Please.

 

[roly_voya]

Utile is a reasonable replacement for mahogany, tends to be courser grain, more red and not as strong or possibly as durable also dosn't take as fine a finnish but fine for deck work. Iroko is nown as a teak substitute but actually quite different. On the minus side it dosent have a lovely fine grain like teak, is a s** to work (you need to sand not plane to a finish and select stock carfully as it is areas of 'wild grain') It is also not as oily as teak so not so durable in wet areas. On the plush side the lower oil content means you can varnish it and unlike teak it will stick! It also has a higher silica content making it much harde so does not abraid from rope or bruise as easily. I find Iroko good where you want a tough durable wood that doesnt need a detailed finish eg cockpit combings or chunky rubbing strakes, rails etc but not for small section or anything that needs a routed profile

 

[jon]

What Iroko are you using!! I find it to be an extremely attractive wood when varnished, some boards can be a little difficult to work, you need sharp tools and tungsten carbide tipped planer knives and router cutters.
It is quite possible to produce fine high quality cabinet work if you select the boards carefully. Its main problem I find is that the colour can be variable so that it is best to source from one supplier and get all you need for the job at the same time buying large boards.
As for varnishing teak, no problem if you use the Epifanes varnishes especially for teak.

 

[jhughes]

I agree, keep your blades sharp and Iroko planes well, you do have to be careful of short grain though.

 

[Spuddy]

I've found that Iroko is a bit coarse grained - large pores but excellent for functional jobs. You can see the mineral deposits as spots of grey in the grain sometimes - takes the edge off planes and chisels but just sharpen more often.
Not got any references handy but my recollection is that sapele not so durable. Sapele and utile can have stripey grain - a strip down the length will plane up lovely but the inch strip next door will pick up ; I'd steepen up sharpening angle on plane iron a degree or two, use it at an angle and finish with a cabinet scraper. Some people like the stripey effect when finished - I'm not so keen. Your planking is varnished I'd guess so check that the look matches. African mahogany used to cover a number of different timbers - as the fellers got further into the forest anything red/brown got called African mahogany.

 

[johnlilley]

African mahogany was most likely used because it is considerably lighter in weight than utile and iroko, it was also more readily available than other timbers (hardwoods) in 1953 and if there is a lot of topside, this would have possibly affected the performance if weight is a consideration. Generally it is not as durable as iroko but probably the same as utile & sapele, but then if that is original planking, it's not done too bad. If the hull is painted, I might consider iroko for the sheerplank as this is the one that eventually gives fresh water decay problems despite it being heavier, however, in thin sections it is inclined to distort over time if it is not fastened at frequent intervals, but stick with african mahogany if it is available for other areas if a considerable amount is to be replaced if weight is important, otherwsie use whatever you want from the choices you have given, just avoid sloping grain, sap, thunder shakes and knots which may lead you to the best choice anyway.

John Lilley

 

[ErikBenson]

Thanks very much chaps ! I am a complete novice with boats and prefer to move ahead with caution. I do have a ready supply of Utile near here -Cognac- and will search out straight grain clean timber. wish me luck. . . . .messing about in boats? great fun.