trimaran removing centerboard

I bougth a sailing shell Mark I 1973 from Tony Smith fabricated in Sandwich Marina Sandwich/Kent and I was lucky to keep it light and the TELSTAR sailed very well. But the laminate of the roof and the centerboard case was bad and was leaking and I had to reconstruct them.
I modified the centerboard cutting a round hole (10cm in diameter) around the bolt of the board and inserted a round plug a little bit thicker than the board. There was never again a drop of water at this point.
Please, do not remove the cb-case and the board or you will ruin the beautiful sailing balance of your boat.
The roof could be cured by polyester injections and a new laminate inside of the cabin. Please test the roof of your boat wether it is strong enough with two sailors on it.
To correct the position of the floats (original vertical) I fabricated washers of 3cm (aluminum) with three holes and fitted them to the lower struts. I gained only a bit more stability with this toe out but the boat looked very good tipping its floats from port to starboard when at rest at the buoy.

Though my TELSTAR was light it always dragged its stern and created a rooster tail. I saw a Telstar with a lengthened main hull - (to 29ft) with a perfect waterflow at the stern.

If you want to sail with four people on board it would be helpful to lengthen to main hull to gain more displacement.
I think this would be more helpful than to remove the centerboardcase.

 

hey manfred

thanks for the very interesting tips !!!

1. centerboard it is decided , i will keep it , but cut shorter in the cabin to the bench level . this level is anyway at the lowest original point so won't affect the water line . the case will be sealed with a flat top cover.
please take a look at my draw ... i was thinking to make a bigger hole in the wood board like 40-50 mm . in this hole a plastic spacer/bushing , wider than the board , basicaly as wide as the case . the bolt is 12 mm diam as i recall and in this way i can torque it well because of the inner bushing. on the exterior of the case there will be 2 big washers 60-100mm diam and all the sistem will be asambled with silicon between bushing and case , washers and case and around the bolt . please let me know your opinion on this setup .

2. the roof seems still strong yet . i have walked over all places on top of it and it holds . it doesn't feel like walking on concrete , but something like a carpet feel ...a little softer walk , 2-3 mm lowering on each step . i have put a guy walking this mornig on it and looked very careful on the movement of the surface when stepping . is this strong enough ? or it should be like concrete with no elasticity at all ?

3. the amas spacers ... i really don't know how it sails , but i will keep an eye on this subject . i did see some other telstars owners had done this mod for raising the floats . from the water mark line on the hulls of resting in the water , seems that the stern part of the floats had stayed out of the water like 10 cm above and the main hull stern water mark is 15 cm deep in the water . i have also seen this stern mod on another forum . how does this look to you ? can you remember how was sitting yours in the water ? this 15 cm stern deep is it much ? i am just comparing the actual situation , not the final result when the boat will be finished and this info is also helpful if possible ... from this point of view , i understand that this boat has a "problem" with poor stern buoyancy and too much buoyancy on the aft and i am thinking af moving all the weight i can to the aft . an example is the battery pack . in original it was under the entrance in the cabin ( 30-40 kg more to the stern zone ) and i want this to move in the aft on top of the water tank some place . another thing i am considering is mount an in board engine , lighter than my 20 Hp outboard mercury ( 50-60 kg ) and put it inside the main hull under the cockpit . this engine is 35kg and will be 1 m to the aft than the outboard ...so again some balance gain to the aft ... what do you think ?

thanks !

 

i forgot about the pic...here it is

 

Great ! But don`t forget the Balsa sandwich in your boat: http://voices.yahoo.com/how-repair-damaged-balsa-core-old-boat-194125.html

 

The Telstar is a pretty nice boat, especially the latest version. I would consider living with the design as is and learn to walk around the CB trunk. A lot of work to remove the CB trunk and provide structural substitution with a dubious outcome. Amma daggerboards on a cruising tri? Not for me. Sail it the way it is. If you learn enough about the performance of the boat, then you may decide to keep it or carry on with your current plans.

 

AR99Kid.
Your Tri is a CRUISING boat. No need for excessive racing efficiency.
However windward ability is not an option. It is a necessity.
Therefore use occams razor,---cut the gordian knot.
Remove your dagger case and install a low aspect ratio keel.
Not too low aspect mind you, but an effective one like Norm Cross's.
Worked well for me on my Piver Nugget. Just my 2c worth.

 

Don't listen to OS7 about ridiculous long keels (just joking seriously OS); if you're going to change the case, do it properly and put a decent dagger board there.
Actually I go along with Tom, leave the bloody thing alone, use the well designed centreboard as is - from Telestar history they sail very well.
Obviously you love to modify things - how about modifying excessive weight. That will keep you happily occupied.

 

It's nice to have a fold out double though, in the place of the CB case.

 

I need to see a layout of the telstar but I think he could get a double with the case.

 

Well first of all just let me say this:

please stop working and start reading and thinking. just don't cut, modify, repair anything before you understand what in the name of god you are doing.
this might be harsh to you but please understand that even if you are an acomplished car tuner you don not know anything about boats or working on them. not even enough to ask the right questions or understand what this wonderful people here are saying. how do I know that? well let's see:
1. you started this thread. you want to cut off the centerboard to have more legspace. first of all you must understand that the centerboard has that weird form by design and cutting it will result in loss of function. as is, the part you want to cut off is sealing the slot when the board is down. cut it and you will have lots of turbulences and water in the boat. not to mention loss of lateral plane. I won't talk about using sillicone on a boat it's just something you do not do.
The really good people here gave you the possible answers: daggers in floats, high aspect dagger in hull or LAR keel. since you won't use the boat in the tidal waters it was designed for it's not a problem to have any of this options. if you take them you must recalculate CLR and the load distribution paths if you go for the floats. but you can not just cut the board as it suits you. put a damm table over it and it won't be in your way anymore.
2. you modified the folding system of the boat. this shows you don't understand that this boat was made to sail with all hulls in the water. if you modified the displacement ratios between main hull and amas by moving their place and/or introduced some dihedral do you know how will it sail in the new configuration? have you even tought of this aspects?
3. you started repairs on the boat. very well. "fiber glass putty" aka automotive filler has no place on a boat this size. you discovered rot. correct procedure is not to "paint it with fiber glass resin" it's cut, splice and epoxy. not to mention the fact that your new plywood is a okume/poplar mix of exterior grade (regardless what holver says I'm just now looking at a sample and it does not have red gluelines) wich needs complete epoxy fiberglass encapsulation to work on a boat. nor that reinforcing the deck is not made by glueing plywood over the existing deck.
4. you want to sleep 4 and sail 6 to 10 with a lot of gear on a 8m multi. said multi is an old tri with winged deck and stepped hull. this is pure nonsense, the boat was designed for 2 adults and a maximum of 2 childs. anything above that is overloading the boat. overloading results in deep immersion wich leads to slamming or even dragging the underwings. it will sail like a dog and sleep will be only possible with really big ear plugs, not to mention safety aspects. you can hold a party or use the boat as a diving platform for your friends but not sail with them. sailing is for you and your girlfriend and eventually another skinny couple that's willing to sleep in the cockpit. loaded displacement for the boat is aprox. 2000kg. 6 people each 70kg is 420kg. boat is already around 1500-1600kg. this without stores and equipment. 10 people would be 700kg. add stores, diving equipment and so on. do the math. this would be like taking your nice racecar, putting a 100hp motor in it loading it with 1000kg of lead and go on the drag track. I doubt you'll like it. Just understand this: big heavy displacement monohull = Hummer. You can do almost anything to it and it will forgive you. light displacement mono or cat = sedan. you can pimp it but carefully. small light trimaran = motorcycle. you do anything wrong you'r in a ditch. you have the worst of it, an old motorcycle. old, and tricky. live with it or sell it. you want a separate shower and toilet you convert the whole forepeak. you want your friends to go diving with you, tell them to buy a RIB and a big motor. they can then take a sunbath on your decks.

This is what I propose to you: get an acount on the romanian boat forums, either barcaholic or capcompas. people there are much more used to real beginners and able and willing to correct your mistakes before you make them. they are also used to the specific problems of owning a boat in romania. you really don't know what to ask here so that you can get an answer you understand because here people think you understand the basics and won't explain them until you ask. It's like going to university before primary school. Let all pride aside and accept opinions from the pros. If they all say don't overload this boat then do not do it. If they say GRP made with polyester is not waterproof and should be either gel-coated or epoxied, listen. If they say the boat has a balsa deck your first order of business is checking for delamination and rot and planing how to seal any hole with epoxy and reinstalling all hardware. asking "how do i determine if my balsa deck is waterlogged, delaminated or rotten?" is not really the purpose of a forum called "boatdesign".

sorry for the long post. I registered just so that I can say this things, I still consider myself a beginner in boat things, and wanted to save another beginner a lot of grief. I will now probably revert to my luker status wich I hold for some years now. Maybe do another 2 posts so that I can use PM's. A good day to all and thanks for the many educational posts, I learned a lot from you guys. Keep up the good work and maybe someday I'll have learned enough to show some of mine ideas.
P.S. please be so kind to excuse any mistakes english ain't my mother language.

 

board case is higher then the bunks but the boat already has one double bunk in the original layout. here are some pictures, forepeak was converted to toilet only.
http://www.multihull.nl/multihulls/used-multihulls/7672.TelstarEP/7672.Telstar.interieurfotos.htm

 

hey rumars !

i really like your point of view and appreciate what you have said . but on some aspects you dind't pay enough attention :

1. please see that i have decided already to keep the case in the cabin , just cut the upper side of it which is only for raising the board . above all this there are also a few testars owners that have done this mod so they can lay a double berth over the case and table . so it has been done with good results ! silicone ...you don't know probably the exact configuration of this boat and parts in it , but that bolt i was talking about was exactly sealed with silicone . and the new mod is the same thing , a bit better ! rotating a big mass around a small diameter bold is much heavier than rotating that same mass around a larger diam bolt because larger surface load distribution . and from that draw you should understand there is nothing compromised only upgraded !

2. folding the amas... you dind't pay attention here also . i have kept the exactly position of the amas when raised ! so the boat is in the original shape when on water ! i dind't changed a thing there ! i was only modiffied the position of the amas when lowered down for trailer transportation ! because they touched the edge of the main hull in the process of raising/lowering them and they dind't go completly under the main hull deck line when folded down ! so the boat was wider than 2.55 m . so the only mods where on the hindges not at all at the fixing points and the position of the 3 hulls on the water !!! still as you could see , there were other telstar owners that have altered the hulls position and get better results than the standard form . but because i am a beginer i have stated that i won't do those sort of mods until i will sail this boat and get the right impression ...

3. fiber glass putty... i am writing in english thou it is not my native language and i don't know all the right tehnical terms . but that fiber glass putty is resin based putty with cutted small fiber glass "hair" in it . it is not a can putty from the store , it is bought form a fiber glass and resin company which sells it to some boat manufatures here. so iti is design for this porpose : boat repair and glueing boat parts ... maybe i wasn't to specific about this in the other thread

4. very good explanation of things and i did get it . like i have said before , i cut some parts of it and i will cut more . there will be some reinforcement done . until now i have lighted it about 85 kg of parts which will be replaced with maybe 40-50 kg and do the same thing ! for example the original kitchen table/desk weighted 10 kg !!! that is not a structural part !!! it is heavy by construction and it was fiber in the boat in a few thin points !!! so no load support or something like this ...only a big bulky heavy part !!! what i will replacing it with , will have like 3-5 kg maximum ! ex no.2 : there were some long ornaments also fiber glass two of them 8 kg/piece also monted in the boat in 4 points big like a pack of cigaretes 1 layer fiber glass ... they where ornaments ! 16 kg out ! i don't need them ...no use for them ! ex no.3 : on the left and on the right of the cabin entrance there where two big plywood panels to support the wiring and some instruments boxes . 12 kg a piece mounted on the boat in some spots of putty . what is the gain here ? 24 kg for keeping some instruments and wires ??? no way !!! those things can stay on better support and much lighter ! this are only 3 examples of unnecessary weight removed . please get my point also ...

5. i have an account on other forums also in romania , but in my country there is not enough info about trimarans . if i don't post on them doesn't mean that i have not read them .here are a lot more experienced people on multihulls and there are more which have done different mods to their boats and can share those opinions ! like os7 said ... and i a really trust this guy , if i really need to take this damn case down , i can and with some mods i still can sail this boat well . there are also some other telstars owners who had done this mod . i have studied it from some time , that doesn't mean that i am completly out of idea if i have asked here also . i like to know as much as i can , that 's why a forum is all about ...share opinions ! so if they have sailed well it can be done . this is just a general talking and asking . i have already made up my mind , but i like to know as many opinions as i can !

6. okoume plywood ... in romania i dind't find any other water prof plywood ... and for my purpose ...small decks... it is perfect . it is not sitting in the water ! and i didn't take pictures of the bottom of it , but there are 2 layers of resin on the bottom of it , before i have put it on the boat. on top of it there agin 3 layers of clear gelcoat and wood paint pigment to match the color of the main decks which were original there ...

7. if i say " i don't know anything about boats " does not mean that i completly clueless ! i have thousndes of hours of readings different pages , but i that doesn't mean " i know " something compare with some pople here which have EXPERIENCE ... and that is for me TO KNOW ! everybody can be smart from reading , but it is something very different to be smart from experience ...

and like you said , i am also a beginner but i want to share and read what others have to say , so learn from reading as much as i can , but like another member here said , learn , make a decision , try it , make mistakes ... then you will really learn !

i will post some pics later this afternoon with my case cuted already ! so there is no way back ...but it is only the top of it !

 

PS: i think i have donwloaded already all the pictures which contains a telstar available on the internet at this moment

that ones are original layout and that "double" bed it is a 95cm wide bed ...that isn't really a double .

here is a more double that i am looking for ... telstar 26 also

a telstar 26 without CB case and a LAR keel under ...

and a "bathroom" also in a telstar

so it is possible ... there are more then one , but i have just put these for examples .

offtopic , i see that you are romanian too !!! where are you from ? can you receive PMs ?

thanks !

 

sweet jesus. I'll try to be more clear.

first of all remember this. the fact that somebody has already done it does not mean that it should be repeated or copied without understanding what the modification means. the simple fact that a user is happy with his modification does not mean that you will be too.
1. the centerboard and casing. they are a unit designed to function togehther. The case provides support for the board and stiffens the hull like a stringer. the case also has to absorb all lateral thrust when going to windward and distribute it to the hull. your centreboard is a very clever design. it is so large because it's designed so that the centreboard has ample contact surface to the case to distribute loading. at the same time it eliminates one of the tipical centreboard problems, having an open slot. now if you cut the top part of the casing down to the floor or just down so you can put a double bunk over it you need to beef it up so that it can absorb the loads, because now the same loads will be distributed across a smaller surface. if you cut it you either cut the board also or let it uncovered because the top part swings in an arch. if you cut the board you will probably need to put lips on the slot. the board is not a tight fit to the case because of mud & associated things. the clearance garantees operation. the board is so heavy to withstand all kind of loads and groundings. yes you can put a big spacer inside and rotate around it. it should be HDPE or PTFE (teflon). the hole in the board should be made bigger, filled with epoxy (and graphite) and recut. but it won't change the fact that you will have water in the boat. every centerboard bolt leaks that's why bilge pumps exist. when sailing to windward a big heavy force pushes the board sideways wich translates in pushing one part of the bolt down and the other up. you don't use silicone on the boat because silicone is the devils stuff and contaminates the surface so that nothing will stick to it when making repairs. you have to grind all contaminated surfaces away before anything will stick. thats why god invented polysulfides (sikaflex) so that boat tuners don't have this problem.
now what can you do so that you can have your nice clean floor or at least big double bunks?
a) cut the top of existing case and the corresponding part of the board, fit sealing lips to the slot and hope they work. beef up case. This is what you decided to do.
b) cut the case down to the floor, lenghten and reinforce it and fit a small profile/high aspect ratio centerboard that fits under the floor. fit sealing lips to slot or use a foam filler piece that can be manually removed.
c) use a daggerboard.

you have to take your decison based on expected use profile. if frequently used in thin water (Danube delta for example) take option a. if used mainly in aegeean and adriatic marinas take option b or c. 1,5m draft is not a problem there. you just have to be careful when going into shoals. beeing a beginner I would opt for b) and use a foam filler piece and a heavy gasketed, snap on top cover. board would be permanently down fixed with a break safety and only reverted to normal centreboard behavior for expected thin water operation. but that's me and I would have to live up to the compromise. hell given the choice I either would do nothing at all or go for the high aspect ratio daggerboard with case engineered to double up as a mast partner. I think a double bunk wider than 90cm is a waste of space, for recreational purposes 90cm is plenty (even if you are 90 cm wide each you still would be stacked one above the other) and while sleeping at 30 degrees celsius she's always far away because it's to hot and sticky so separate bunks are ok. plus you don't have to untangle yourself from her frightend embrace if the anchor drags in the middle of the night. not to mention those nice big decks of yours, just take one of the big blue inflatable beds and sleep outside it's probably cooler than in the cabin. at least in the med.

if you cut the case already fit the board and see how it swings. I think at least one part of the board will stick out of it now when moving. take pictures.

2. for trailering the lower struts were designed to be completly removed and amas to sit on top of the fenders. what the hell if nothing changed just hot dip galvanize the parts and mount them.
3. well you shure ain't clear what "putty" you are using there. from the pictures it looks just like automotive polyester filler with chopped fiberglass. and I cant find it in the catalogs of the two big suppliers polydis and rompolimer either. what exactly are you using? it should be epoxy based to be of use, and it's cheaper to use liquid epoxy and microballons to make your own. anyway what's the surface treatment on your boat? in theory it should be gelcoat but on a boat so old you never know what previous owners have done.
4. from what I could find on the internet the boat has an inner liner. could well be that the inner liner is structural (that means all furniture) or not, the "ornaments" you removed could be local reinforcement for deck hardware or other stress points, the plywood panels could act as partial bulheads, etc. I really can't say anything without actually seeing it or having construction documentation. You have the means so you could rip everything out and repalce it with infused and autoclave cured moulded carbon fiber/honeycombe sandwich parts. I don't have a problem with that as long as you know what you are doing. not in the fabrication department but in the structural engineering. I'm pretty sure you can fabricate anything you want but be advised that furniture is often part of a boats inner structure. they are not bolt on things like spoilers they are structural members like the cars rocker panels. if you change them you must engineer the load paths and laminate strenght or use an isotropic design like plywood or chopped strand matt GRP.
5. well just present your restauration on the romanian boards and you will be surprised. the fact that there are not a lot of tri's there has to do with the fact that there are few boats overall and folding tri's are something special. it has to do with our communist past and so on. but general boatbuilding and boat design principles are known, boats are beeing designed, buildt and restored. there are also tri lovers, they are only hidden and sail monos because that's all they can afford. You don't think I'm drooling over my laptop when I see pictures of mister Baigent's Sid or a nice Buccaneer? It's only that I live in an apartment, have a car with a 350kg towing limit and can't afford to regularly trailer 800km to the nearest sea. That's all that conspired to keep me from going bersek over a stack of plywood and a barrel of epoxy. And I'm not the only one. Even my girl said she wants a boat that "goes fast", "does not heel much" and "has wide decks preferably netting". jesus I'm so over the edge I even got the proa virus, wich people say is uncurable until you owned one and sweared the whole calender of saints against it. (It is also said even that does not guarantee successfull curing and often leads to a mutation that delivers you blindly in the arms of a radical faction of one of the specific proa philosophys wich you will then defend until death as the only multihull truth.)
6. we either got a communication issue or a big problem. gel coat and plywood do not mix. plywood only likes epoxy resin. as for painting ply with resin (epoxy I hope) that's bogus. You either do a propper job and use fiberglass or do not do it at all and only paint it. it's almost impossible to avoid pinholes in a thin coat and a thick enough coat is to brittle without FG. and poplar and okume are not exactly classified as "durable" in a marine environment.
7. in my opinion forums are here so that I do not make mistakes and pay for them. but fortunately boats are always a compromise, so if I make a mistake I can change the design brief and call it a success. Like "Yes sir the decks are intended to be soft and springy, that's good for your feet when walking on deck in a steep chop it's suspension. Yes the bilge is supposed to be full that's where we do the laundry, just ad some detergent and the boat does the rest". I'll only admit to failure when the boat sinks and afterwards I'll call it a successful disposal of a piece of crap. that is if I survive of course.

I'm from cluj and I can recieve PM's after some posts even send.

 

I think you have already found best support by Telstar owners who have experience with some of the modifications that can help you: http://www.telstarowners.net/bb/viewforum.php?f=23&sid=d56a4c042d59ed05563e80e999f5ed21