[New Guy, Older Boat (Tennant Turissimo 9)]

So that's 160x120 actual, with 3.32mm wall thickness. Is there any sleeving?

 

Randii

[New Guy, Older Boat (Tennant Turissimo 9)]

i used to sail a "borrowed" GBE from a mate and one of my regular crew was an ex german airforce aircraft enigineer . he sprayed the inside of the crossbeams with this fog thats designed for protecting the inside of aircraft wings from corrosion . Quick squirt either end of the beam and it drifts through and coats the surface . It was a corrosion X product but cant remember the name of it 

CX is good stuff. There are various formulations, but the HD mix is probably best for open-exposure ocean use. http://www.corrosionx.com/corrosionx-products.html I'm not sure how well any of these films hold up to open weathering. Some kind of end cap might help?

 

Our main beam is 160 by 115, same as the mast.

Any idea on the thickness of your extrusion. Freedom?

 

I'm going to play with Beam Boy a bit: http://www.geocities.ws/richgetze/. That's a good bit further towards the deep end of the engineering pool than I usually wander, but nothing ventured, nothing gained...

There's at least some partial consensus that the crossbeams were under-specified in early GBEs. The Wildfire and T9s I looked at have much larger-dimensioned beams. Perhaps Malcolm (or builders) up-specced on subsequent boats?

 

After running down a couple of water leaks, I have a dry boat (hurrah!). Next stop is to get the hulls off the trailer onto dollies for some bottom work and trailer repair.

 

Randii

[New Guy, Older Boat (Tennant Turissimo 9)]

Martin, my T9 does indeed have the shorter ‘bury’ on the main crossbeam hull socket (improved access forward vs. less engagement with the ring frame)... and Tennant's floating mastbase/dolphin-striker. The forward and aft beams hold this boat together, since the main and mid beams aren't affixed to the hulls (at least before the rig is tensioned). I have looked at your slick composite beams, but hope to keep in much simpler (as my composite skills are MUCH more basic!). Thanks for breaking down the loads... I was not visualizing them all. It really underlines how involved multihull crossbeams can be!

 

My beams seem generally dimensionally similar or larger to what Tennant specced, but I will be Googling to verify the intended wall thickness and section weight. Getting the boat off the trailer and into the water is more a priority than is identifying upgrades.

 

Randii

[New Guy, Older Boat (Tennant Turissimo 9)]

I'm providing the info from the study plans for reference. I'm working my way across the web trying to identify the extrusions I have so that I can compare them to what Tennant specified.

 

The GBE study plans list the crossbeams twice, once in the Fitting List (FWD 100mm, MAIN D15, MID 100mm, AFT D15)
…and another with greater specificity under Aluminum Extrusions. They don’t exactly match, but still have value in context.
- FWD: round, 88.9mm x 88.9mm (weight/m: 1.85kg)
- MAIN: ellipse, 152.4mm x 114mm (weight/m: 3.43kg), D15
- MID: ellipse, 133.4mm x 100mm (weight/m: 2.77kg)
- AFT: ellipse, 152.4mm x 114mm (weight/m: 3.43kg), D15

 

The T9 study plans specify:
- FWD: round, 127mm x 127mm x 3mm (weight/m: 3.42kg)
- MAIN: ellipse, 161mm x 112mm (D16 Yachtspar: weight/m: 4.24kg), each end sleeved with 400mm D15 (a short sleeve for a short socket)
- MID: round, 101mm x 101mm x 3mm (weight/m: 2.71kg)
- AFT: ellipse, 190mm x 120mm  (BS 21, weight/m: 4.35kg)
I don’t have the full T9 plans (sure wish they’d have come with the boat!) but may prioritize boat bucks for that.

 

I appreciate this forum!

 

Randii

[New Guy, Older Boat (Tennant Turissimo 9)]

I measured my crossbeams and wall thicknesses today. There's substantial variance in the wall thickness, some attributable to the forming process, and some likely a result of dings and age. Accordingly, I'm listing estimated average (min, max) and notes:
- FWD: NG-37 egg shape, 170mm x 115mm x 4mm (3.74mm, 5.45mm)    
- MAIN: ellipse shape, 178mm x 110mm x 4mm (3.6mm, 6.1mm)
- MID: flattened oval shape, 127mm x 83mm x 3mm (2.52mm, 4.1mm)
- AFT: ellipse shape, 178mm x 110mm x 3.5mm (3.1mm, 4.65mm)
My main and aft beams appear to be formed from the same die… that will be handy if I need to sleeve or replace the main beam. Due to the female hull sockets, I’m fairly committed to the outer profiles of the main and mid beams. Reworking either of these beams would be non-trivial – reworking the forward or aft beam less so, since the cradles and brackets are well-exposed.  

For reference, NG-37 Isomat specs are here: http://www.rigrite.com/Spars/Isomat_Spars/Isomat_Masts/NG37_mast.php

 

I have the study plans for both the GBE and the T9, but I'm still sorting out a matching table for these. The GBE text is internally consistent, but the T9 text has internal inconsistencies and some gaps (specifically around section weights and wall thickness). Weight is important, since the instructions say: “If the above extrusions are not available, go to the next biggest size, do not use lighter extrusions, do not use thinner walls, however some reduction in the outside dimensions would be acceptable.” With more analysis yet to do, my first sense is that:

- the upgraded front crossbeam on my T9 seems pretty stout
- the rear crossbeam looks slightly under-spec in dimension, but likely over-spec for thickness

- I'm a little concerned that MT specced sleeves for the main beam on the T9 and that I have no such sleeving
I've seen Internet evidence of some main beam failures... obviously, with the rig standing through that beam, that's the least preferable one to fail, structurally speaking. I've also seen postings of the front beam failing (not surprising if flying a headsail off a prod cantilevered forward). Any crossbeam failure would be a bad result... but are the mid and aft beams anywhere near as stressed?

 

I'm curious what this means from the study plans: “The main beam and the rear beam are two-piece extrusions, i.e. they are split longitudinally.” How were they split on original GBEs? My T9 beams are definitely not split.

 

Randii

 

Tennant's aluminium cross beams are under-engineered in my experience. We had problems right away and I have come across a score of other owners with more or less severe problems to report.

[New Guy, Older Boat (Tennant Turissimo 9)]

Thanks, Tim... that seems eminently possible at launch or a few years back (the boat was first registered in '84).

With 34 years intervening and 4 different extrusions, I suspect finding matching extrusions will be challenging.

 

I'll search, but I may also need to prepare a Plan B, and at first glance, that looks like a composite insert.

 

Randii

[New Guy, Older Boat (Tennant Turissimo 9)]

I checked, and there is no sleeving inside my T9 crossbeams. I've googled a bit with respect to what's involved with that... since my beams are oval or egg sections, there's no perfect 'stock' section available to insert. Short of having a Naval Architecture spec it out, is there any sort of best practice that's been done for the existing GBE fleet? Seems like the beam would receive highest loads at the inner-most hull/beam interface/connection/clamp and taper either direction along the beam from there.

 

As noted above, I don't think this boat has been sailed very hard very often, so failures haven't shown up yet. I'll ask the previous owner about the 'under-spec' front beam and whether it failed or was just replaced.

 

I will web-search more on this... since the beams are extrusion-formed, coming up with a composite insert seems possible, though certainly not simple. Maybe use the existing beams as a female tool and bladder-form reinforcement inserts -- I wouldn't say the T9 beams are 'roomy' but they would seem to have SOME room. Then again, why not reinforce the OUTSIDE of the beams (access is certainly easier for reinforcement and creating tube clamps).

 

Randii

 

http://crew.org.nz/forum/index.php/topic/1959-gbe-broken-bmain-beam/

"Hilton, If the main beam was done correctly it should have had a sleeve inside it which runs the length of the section inside the hull and out up to about 300+ outside (depending on how much the last guy who built it had spare). This reinforces the highly loaded part where the beam leaves the hull (and where the dolphin striker bolts on underneath). It might be that the sleeve is still intact which is why the main beam didn't join the dots and come completely apart. The sleeve is usually made from a section of the same material as the beam but with part of it cut out length wise so it can fit inside."
 

http://crew.org.nz/forum/index.php/topic/15012-gbe-fore-beam-replacement/

"on multis all those wracking loads are at the corners and the strength there needs to be at least double the mid-beam
so with alloy beams you can either use a simple section, that's far too strong-heavy in the middle or find a way to get double or triple the strength at the ends..."

"...alloy beams that aren't telegraph poles in the middle are going to need to be about twice as strong at the ends somehow
sleeving being the obvious solution"

"... cut these 1mtr sections of the old beam in half to use as half molds, wax the inside, and glass in a few mm of boat cloth 1 mtr long, half-cure with the tubes strapped shut and some blown up wine bags against dry? cloth? forcing the wet cloth to shape, then deflate and remove bags to lay 900mm carbon strips inside that, half-cure again with the bags, lay more 700mm carbon, half-cure 600mm etc
try and bake your final mold  on a the dash of a closed up car on a hot sunny day, (reaches about about 50C), all day
crack them open the next day to remove your glass insulated carbon sleeves, ready for sanding rough, latering in an epoxy, adhesive mix and slipping into new beam ends
not going to be quick or pretty but the end result won't be seen and can be as strong as you want it"

 

https://www.boatdesign.net/threads/k24t-versus-buccaneer-24.27493/page-2

"The alloy crossbeams being particularly problematic, as suitable stock tubes the right length are not available here and mast sections the right size would need to be sleeved at certain points because the wall thickness was too thin."

[New Guy, Older Boat (Tennant Turissimo 9)]

I'm not entirely certain on what is sealed and what is not, since the boat is PPG-painted entirely on the outside and mostly on the inside, but I believe her to be epoxy-laminated and epoxy-sealed on the outer skin. She's finished clear on much of the exposed Okoume strip-walls below, with some painted surfaces between the main and mid-beam. I'm not sure how to differentiate varnish and epoxy inside?

 

Daggers are ripped/flipped/laminated wood -- likely cedar. The previous owner stripped the side of one of them in an effort to squeeze past a jam in the starboard dagger well, so I can see through the 'glass for its length. The tips have been either extended or cut about a foot up, presumably as a sacrificial 'fuse' in case of grounding. Fixing the jam properly is a planned project, then that board will get a new skin. I can't say how the rudders are built, but I'd guess them to be of similar construction. They fit a little more loosely in their cassettes than I'd like, but they work for now.

 

All cross-beams are aluminum... I haven't peeked inside to see if they are sleeved. The front beam has been upgrade to a NG-37 Isomat section - this is closer to what Malcolm originally specced (the previous beam was well under-sized). After some quick percentage size math, I'm surprised at the variance between plan and as-built specifications on the cross-beam sections. That's probably a commentary on what was available in NZ vs. what was easily available where this boat was built in the USA.

 

This T9 was built in the early 80s and registered/launched in '84. She was born on the Pacific Coast and then received a major refit in the early 2000s in Florida, before being trailer-ed north to Canada. She has more wear from the shed than the sea since then, I think...

 

Martin, I will be spending some time on your site... great info there! I researched hard into GBEs before buying this T9, and somehow missed yoru pages.

 

Thanks for the welcome!

 

Randii

[New Guy, Older Boat (Tennant Turissimo 9)]

I had some difficulty starting an account, but the administrators and programmers fixed whatever was wrong, so here I am! I appreciate their efforts.

 

After years of beach cat experience, I have been looking for something a bit larger. Ian Farrier's work has impressed me for years, but I really like catamarans. After a summer of searching, I got hooked on the look and feel of Malcolm Tennant's boats, of which there aren't a ton in North America. I did some travelling to visit a few boats, and a Turissimo 9 followed me home on a trailer. 3000 miles, an international border, and a bunch of states later, I'm in Central California dusting off this classic Okoume double-diagonal epoxy classic.

 

There's minor delamination around the cockpit edge, in the carvel-bent decking, but the rest of the boat and rigging is in pretty solid shape. One of the windows leaked and has slight delamination inboard, and we got some road damage to the antifoul and fairing at the bottom of one hull, but everything else is just rejuvenation that you'd expect to need to do after rescuing a boat that spent too much time in the boat barn.

 

I'll be visiting here to read up and ask questions about the care and feeding of  wooden boats. There's just not a ton of support here stateside for plywood-built boats. Gel coat and fiberglass rule the day, and that's not what I could find in the 8-10m range of catamarans.

 

My planned usage is exploring the estuary upstream of San Francisco, and working my way out to the Bay as my bigger boat skills develop, eventually thinking about coastal cruising down California or trailering down to the Sea of Cortez and exploring Baja. These are big dreams for the future, but reality right now is repairing the scuffs and delaminations, going through the boat's systems, and getting out on the water in early 2019.

 

Thanks in arrears -- I spent no small amount of time here when I was shopping (Paxfish's Wildfire was one of the boats I visited on the other coast) and considering purchase options. Also, thanks in advance, as I know there's much more to learn.

 

Randii