A Photo & Discussion Forum for Wharram Design Enthusiasts
After a summer of sea trials and preparations, we (my wife Kathleen and I) left Hornby Island BC on Sept.14 bound for San Diego using the offshore route. If only we had left a week earlier while the weather systems were more or less normal, we could have avoided all the unseasonally heavy weather that caused us to go inshore and seek shelter when needed in whatever port was nearest. The weather has been dreadful; 4 days of storm force winds and 7 at gale force. Even when winds were forecast at N. 5-15 we found ourselves in a whole gale (maybe more, we don't have wind instruments) rounding Cape Blanco at night and doing 8-9 knots under bare poles. Right now we are in Humboldt Bay, California, waiting for a weather window for rounding Cape Mendocino. Kattu has performed well under heavy going but for one unsettling issue...the movement and thumping noise of the rear beam. I have 8 turns of lashing on the insides instead of the six called for in the plans, as I had read of this problem in one of the older forums. All of the lashings have been re-tightened twice now, and there still is some movement. Off Cape Blanco I could have stuck a finger between the beam and it's rubber pad at times. I would sure like to hear from others with offshore experience whether this is just a normal situation for a Tiki 38 or do I need to add even more turns of lashing.
Thanks all for your thoughtful responses...back in port now after 6 days at sea, in Santa Cruz. Point Conception is getting closer! It won't be a minute too soon as we have been near hypothermic in the dense fog and wind out there. Dave, I added the extra turns of lashing before departing the last anchorage, and all has been quiet so far. I think I will replace all with the very best rope I can find. Maybe go up to 10mm.
Rod, I'll take you up on your offer. It may take us a week or more to get there, as we'll want to relax a bit on the way once in warmer waters!
Neil, make any use of those videos you like.
Tiki 38 beam lashing update:
Doubling up on the rear inner lashings worked so well, that by the time we got to San Diego I took a leap of faith and converted the inner lashings on beam 2 and 3 to Dynema. I had previously thought the new high tech ropes would cut into the beam; but I kept the 9mm diameter, which although overkill strength wise, provides the cross sectional area to spread the load out so cutting into the beam turned out to be a non issue. On arriving in Mexico, I doubled up all the lashings.....outside as well. I have to say the boat immediately felt much better sailing in stronger winds and large waves, with a lot less movement of the masts as well. The rear beam inner lashings now have 12 turns of Dyneema in two separate wraps so if one should fail, there is a backup. Heading north along the Mexican mainland coast recently we encountered some very heavy going in the vicinity of Cabo Corrientes. The seas were the size of houses, with no pattern, and very close together. A 2 knot northbound current against a gale force northerly combined with the cape effect created a hell that we were beating into for 12 hours. The wind was so strong it shredded our 6 month old heavy nylon bunting flag! During this time, there was no noticeable movement in the beams, and there was no sound at all coming from the lashings or the beam pads. At this point I feel that the flex issue is a load of BS. If a heavily loaded component is free to move, then the stress at the end of it's range of movement is going to be a lot more than if it hadn't moved in the first place. Also, what appears to be the rear beam moving is in fact the hull twisting down from under it and this can't be good. At any rate, the lashings as shown in the plans are completely inadequate, needing re-tightening on a regular basis with the ropes getting stretched thinner in the process. It was seeing how thin these ropes had become compared with new rope of the same diameter which promted the switch to Dyneema. The original lashings were high quality polyester double braid.
This will be put to a real test soon when we head across the Pacific to French Polynesia in a few weeks.
I just wanted to share my experiences on this problem for whatever it may be worth: time will tell if my new approach is correct!
Thanks Alf for sharing your findings on this issue.
I also found my Tiki moves most in a quartering sea. Far more than going to windward - unless you fly the whole boat off the top of a wave and stuff only one bow into the oncoming wave!! Then the lashings squeek under the big strain.
Going off the wind there is much less rigging pressure on the structure than going upwind - so the hulls and beams are able to move more with the sea.
I agree a tighter lashing is better. there is enough movement in the slight stretch of lashings and flex in beams. Cookie moves as a whole except in the biggest moments of strain.
Good luck with the rest of your voyage.
One of the things I do not like on some Wharram designs is standing the mast on half-beams. This places the down thrust of the mast-step on the inner gunnel and the up thrust of the stays on the outer. The T38 uses this ahead of the rear beam.
The comment on releasing the stays before tightening the lashings shows that even at rest the mast/stays are stressing the beam attachments.
Under way the situation is worse.
As to the degree of flex at the beam/hull joint I agree that a minimum is best. Mine is now at the can-feel-it but can't -see- it which I think is best.
Bon Voyage from me too !
Maybe a silly question but in my eyes an obvious one: Has anybody ever tried to fix the shrouds of the main mast to the beam only and not to the outer gunnel? Stability of the mast should be o.k. if you consider the geometry of monohulls. And this would fix the issue with bringing a torque to the hull by lifting the outer gunnel and pushing it down on the inner side. Just an idea!
Fair winds for all of you
Yes I did it. Replaced the four and a half crossbeams of my P31 with three full ones , mast on No. 2, with shrouds to end of beam. Perfect !! Saved over 100 kg weight and costly timber and transformed the sailing. But if you sail another design you will have to decide for yourself if it is appropriate.
Kim I replaced my old half beam with a full beam in the same position [centre of boat] My mast is stepped on a fore / aft beam [ really a long mast step] between beam 1 and 2. The foot is 0.5m in front of beam 2 but raked aft by the same amount so the head is in line with the beam. This gives a "sweep back" of 0.5m to the shrouds. I also have a backstay. I think the real benefit is to boats with the half beams. It was for me the combination of movement of mast step combined with movement at the shroud plates that created a major problem.
I think the benefit to other boats would be much less. The benefit to a T26 I think would be too small to justify the work involved. It is really only justified where there is a lot of movement in the hull - ie where the lashings need regular reworking.
And as you point out you would lose your shroud angle on a t26 - without a backstay this mast would come down !
your lashings are not tight enough. you must use blog and tackle to tight them. you have to redo the job after 500nm if you used the ropes. do not use spectra rope. use regular yacht braid rope..
@Hans: What is the issue with spectra rope vs. "regular" polyester brais rope? Does your comment also allpy for Dynema and other Kevlar/Aramid-related fibres? Is it the low stretch ability?
I am just curious abour your opinion.
Thanks and regards and always fair winds
The spectra (Dyneema) is a VERY low stretch line. It is difficult to get it tight enough to stay tight. The good poly double braid has enough stretch that you can tighten it up into its' stretch zone with the frapping turns. prefer to use spectra for the frapping turns as it is very slippery and does not stretch much. If the spectra does not have enough load on it it will creep and slack. It needs to be tensioned enough to settle in. This is what John Franta of Colligo Marine told me.If your poly lashings are stretching thin I would assume either porr quality line or too small a diameter. We use a truck too tension the spectra frapping turns while applying dish soap and working the frapping turns with levers to avoid any slack spots in the frapping turns. We set our boats up tight. This means that our rigs stays tight and there is very little movement at the beam blocks. We use a 1/16" thick reinforced neoprene pad between the beams and blocks. The beams and blocks are pressed very tightly together and without the pad when the beam/block interface moves minutely the noise is horrendous. The pad eliminates that noise.