Steaming and laminating

[ianc1200]

I'm doing a major rebuild of my estuary cruiser, Straight Across. She is a 30' version of the ARC Marine Everyman design, built in Littlehampton in 1951. We have owned her 40 years in December, my grandfather also owned her 1956 - 1974. This is the third time in our ownership we have taken her apart, although the two previous times were on the Thames at Hurley, with the work done by Peter Freebody. She is now in NE Essex at Titchmarsh Marina, Walton on the Naze. As an aside she is about 100 yards away from where Simon is rebuilding Chance/Token. We only restarted in earnest a couple of weeks ago and are having an interesting time. My intention, having done this before and not wanting to end up with rotten oak in a few years, is to replace the steamed oak timbers with laminated iroko - using iroko I had left over from the 2002/3 rebuild. Whilst this might sound simple, what we found was the timbers ot only curved downwards, but also forwards. The 1/4" iroko bent following the shape of the hull, but cracked when we attempted to twist forwards. We then steam bent some oak in, with the intention of reverting to laminated iroko further back. Today we had a go at steaming the laminations, made much easier to get in but also noticed a third complication - the laminations really should be tapered to match the hull such that there is a gap at the aft end of the laminations. Hoping to learn & get right the more we do. To steam we're using a timber long box and a wallpaper steamer - appears to work. The laminations mainly aren't in the correct place, today trying to get some pre bend in them.
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[Hacker]

Either steam bend oak or make laminates around a former. Steaming a laminate rarely works (and if epoxy it will let go). The other option to a steam box is to use cylindrical plastic bags (we use ones from catering suppliers). The advantage of these is that you can, if needed, steam in-situ.

 

[LittleSister]

Either steam bend oak or make laminates around a former. Steaming a laminate rarely works (and if epoxy it will let go). The other option to a steam box is to use cylindrical plastic bags (we use ones from catering suppliers). The advantage of these is that you can, if needed, steam in-situ.

Yes, I know little about woodworking and boatbuilding, but making a laminate and then trying to bend it sounds all backwards.

You speak of making a laminate around a former. Can it not be done in-situ, and then (I imagine in my innocence) it would be the right shape from the start and save the trouble of making a former?

 

[Hacker]

If you could get sufficient clamping pressure along the whole length then you could. Just remember to isolate the former (or whatever structure you are using) with plastic or parcel tape.

 

[Wansworth]

Yes, I know little about woodworking and boatbuilding, but making a laminate and then trying to bend it sounds all backwards.

You speak of making a laminate around a former. Can it not be done in-situ, and then (I imagine in my innocence) it would be the right shape from the start and save the trouble of making a former?

In my mashford 4 tonner I did just that,sistering sbtwith four strips laminated in place one at a time pinning one strip to another……double bend to boot…without epoxy

 

[debenriver]

Usually much quicker to steam bent the timbers provided you can get them into place OK under the beamshelf and bilge stringers.

Iroko steams quite well too – Dagless used Iroko steam bent timbers in many of their Fleur de Lys class motor yachts. Worth trying.

Cheers -- George

 

[14K478]

Usually much quicker to steam bent the timbers provided you can get them into place OK under the beamshelf and bilge stringers.

Iroko steams quite well too – Dagless used Iroko steam bent timbers in many of their Fleur de Lys class motor yachts. Worth trying.

Cheers -- George

If Peter Brown did it (Dagless) it’s OK. Wish he’d told me - mind you, I never asked him!

 

[ianc1200]

Iroko steams quite well too

That's interesting - I'm being told iroko doesn't steam bend well, due to the grain not running straight.

Either steam bend oak or make laminates around a former. Steaming a laminate rarely works (and if epoxy it will let go). The other option to a steam box is to use cylindrical plastic bags (we use ones from catering suppliers). The advantage of these is that you can, if needed, steam in-situ.

I've seen the video's of people steaming using "plastic bags" as the Americans can them. Struggled to find here until I realised called "layflat tubing" or "poly tubing". Would be difficult between beamshelf & hull & two stringers and hull, but definitely an option when renewing beamshelf.

Yes, I know little about woodworking and boatbuilding, but making a laminate and then trying to bend it sounds all backwards.

You speak of making a laminate around a former. Can it not be done in-situ, and then (I imagine in my innocence) it would be the right shape from the start and save the trouble of making a former?

Round a former would be very time consuming if having to make a former for each steamed timber. Then there would be the difficulty in getting it in, we've steamed a short one in oak but now can't get out to cut a scarf.

In my mashford 4 tonner I did just that,sistering sbtwith four strips laminated in place one at a time pinning one strip to another……double bend to boot…without epoxy

Essentially this is our intention - to get one in place, pin it using copper pins to the hull, but then pin/epoxy three further iroko laminations. This video has interesting ways of holding in place using the old nail holes and temporary long screws. He also tapers the inner and out lamination to match the hull curvature fore and aft.

 

[38mess]

What a great video. I could smell the wood, vanish and tobacco almost.

 

[fisherman]

I have a tube from an airbeam tent for steaming, brilliant. It cost £30 to get a new one, this one had a leak, so gash. Come in all sizes. Good thick material. I made formers with 18mm ply. Cut the curve about 100mm wide so you can clamp all along. With care you can recut to make the next one. I used these for steamed and laminated. Some I steamed, laminated clamped, and glued later, for knees eg.

 

[ianc1200]

Not progressed with the steam in a bag idea. At the beginning of the week steamed a solid 1.5 x 1" and about 5' long piece of iroko in - did it but was an effort. Last week I had built a 14' long steam box specifically to steam iroko laminates. However on Wednesday cut 13' long, 1.5" wide, and 3/16" iroko laminates to steam, but they were so floppy had a go at putting them in unsteamed - it worked a treat, and as they were so floppy the height of the tent over (about 5') wasn't a problem either. From where we wanted to put them in, the 2nd stringer down, they bent in a big arc back onto the boat. Then we had another eureka moment, getting the 1" thick laminates between the stringer and the hull was difficult, but a couple of wedges banged in underneath resolved that. On Friday we glued them up in the container and transferred and put onto boat - more wedges and effort, and they were in. We then either clamped to remaining planks where planks removed, or used the hex screw with a block as used on the YouTube video noted above to squeeze the laminated together/onto the hull. we need to perfect how to get the laminates in line - they move laterally against each other. But then started nailing/roving. The big impression I had was after how time consuming the nailing process was - I employ a skilled shipwright to help me three 4 hour mornings a week - I'm going to need extra & longer help to get nailing done. The new frame is the one on the right below.
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[fisherman]

I had to steam 8m long, 40mm X 90mm iroko
I borrowed the steamer at Cygnus, steel box with A frame one end, bonfire under the other, the timber was submerged for half the length
We bent it round a hull in the workshop then took it to ours.

 

[ianc1200]

Fisherman, how long did you steam it for?

 

[fisherman]

Fisherman, how long did you steam it for?

Hour and a half or better. It wasboiled, mostly

 

[fisherman]

Hour and a half or better. It wasboiled, mostly

I found that when I made a steam chest, out of ten inch stainless pipe, it lost heat too much, even when lagged.

 

[burgundyben]

Interesting that the 3/16 Iroko was bendy enough.

 

[ianc1200]

Interesting that the 3/16 Iroko was bendy enough.

Was shocked - had constructed the steambox (with 4" mineral wool around) specially to steam the thin strips.

 

[rotrax]

In the early 70's while at Banbury I saw an ex working narrow boat having a few 2 inch elm bottom planks fitted. The boats construction had 'U' channels facing each other along the riveted iron hull bottom. 2 x 4 inch elm planks were cut to size, steamed and then using a series of well practiced moves bent down in the middle whle the oposite end was tucked into the channel. A big hammer and substantial pressure was needed to ensure a tight fit. Tooley's Yard and dry dock can still do these jobs. "Knocking a bottom up" was a severe blow to a working boatman. IIRC, 'Chalico' a mixture of horse manure and pitch was used as a sealer. Both, especially the former, were in plentiful and free supply in the days of horse drawn boats on our canals.....................

 

[lexi]

I have steamed a laminated stem in many pieces bent into a former. Sessile Oak. Left a week and epoxied up no problems. The steam dries the wood like crazy.. Thin Epoxy, then thickened

 

[ianc1200]

Progress - some full length steamed oak, some scarfed (because of restrictions of height over due to tent) & three to right in photo laminated iroko. Holding laminations against hull has proved a problem - we can't copper nail until set as top laminations split when nail is hammered through. We are going to use dry wall screws & blocks on outside for the next frame.