what does a Lloyds classification mean anyway?.

Discussion in 'Class Societies' started by tugboat, Nov 5, 2012.

  1. tugboat

    tugboat Previous Member

    Tunnels- yea its 26 ft l.o.a. it is steam powered...2) 10 hp @ 500 rpms.
    turning two 20 inch props..i have no idea about bollard pull since it really isnt going to be worked all that hard--maybe the occasional tow, and to tender a houseboat ...so we are talking a balance between economy and power...if i was going to use a diesel i might use around 100-150 hp..not more for fuel costs..maybe gear the diesel 3:1 or so. but sincxe its steam they need BIG wheels and thats why im using twins...the prop aperture needs to be able to take a 45-50 inch wheel if using a single steam engine...thats not going to fit under my boat--so twins are the only option...
    they are very pwoerful though..hp per hp hands down better than a diesel, for torque. any suggestions?..i.e..laminate schedule? why not core below the waterline?..its proven its not foam core...its polypropylene...big difference..
  2. tunnels

    tunnels Previous Member

    Now i have a little better understanding of size and what your about !! I had envisaged something 3 times that size and a work boat pushing and pulling etc etc and even getting squashed between a wharf and a ship .
    Now i can get my head around something smaller !! so you would use twin propellers ?? and rudders ?? are the props shelded at all ?? Do you have any pictures just to see where and what its all about ??
    THE first company i worked in we had a boat called Scuppers that was a in board or outboard tugg looking type boat !! the inboard was normally a 2 cylinder Bukh diesel !! only very few were even made . its not the type of boat New Zealanders were ever into . if it didnt sail no one was interested then came the power boat boom times as age began to catch up with the old sailers and there legs and joints complained louder with each passing year so they drifted into launchs .
    But thats history !!.
    Resin deffinitly Vinylester and the 3 glass types chopped strand matt !! with good old reliable woven roving and the use of unidirectional glass to add durability and flexability throughout !!
    The woven is availible with a layer of csm on one side so makes a quick way to do multi layers .
    Core yes you could use a core for what you going to b e doing but i would 100% recomend Balsa wood end grain and only used in the topsides of the hull ,preferably above the water line !!. Having Bulwarks ??
    The rounded shapes that would be under water sections will have there own rideged strength and using glass frames from the keel to the underside of the deck would be strong , durable yet able to flex and have movement if hitting a rock or tree or what ever .
    Again water ballast is worth serious consideration for getting down and pulling hard , but when just going from one place to the other lighten the load and go !! The tanks would be all glass and if totally below water level could fill by them selves till full then shut off to empty could be pumped of aopen the bottm valve and pressure and blow the water out and shut the valve again Is nothing new Yachts been using it for ages !! even big ships use water ballast and some of the old sea planes had flooding chambers , inflatables to make them stable in the water some have flooding underfloor chambers and when they take off all empties out the back very quickly .
    Ok its all interesting let me see something like you wanting and will think about the glassing issue , wouldnt be diffucult !!:D
  3. tugboat

    tugboat Previous Member

    Thanks tunnels..here are some pics..posted on previous posts too..forgive my poor quality renderings..ive only been doing cad about a year so its not the greatest and im self-taught mostly. specs- loa 26 ft beam 10 ft bottom is rockered or "cambered longitudinally to 1 ft over the 26 ft.

    Attached Files:

  4. tunnels

    tunnels Previous Member

    Can you give a better look at the keel detail like the actual size and where the prop shaft and the motor will sit !! plus a middsection cut through veiw with hull shape and deck and cabin sides and roof eetc etc just to see the fesability and degree of difficulty of glassing such a shape will have a long tube for the propshaft with a bearing at the back and gland at the front !! what about thrust fore and aft what do you use there?? and the rudder has it got a shoe set into the bottom for the rudder shaft to sit into ?? hydralic streering with a push pull ram at the back below deck level and a access hatch flush monted to service at area ?? again a bearing , tube , and a gland with a deck mounted bearing with a square ended shaft so a tiller can be mounted in the event of a hydralic failure. The pulling post goes to where ?? part of the push would be on the deck but the bottom of the post is how far down and what holds it from wanting to climb out of it place ?? same with bollards just in front of the wheelhouse they could get some serious tugging In the event of a major motor overhauls and or replacement maybe the parts in around and above that part should be made to unscrew ,unbolt, disconnect and be lifted completely clear of the boat in as bigger pieces as possible better to think about what could happen and needs provissions made for now at the planning stage then having to hire a chainsaw later to get to the dipstick to check the oil !!. :D
  5. tugboat

    tugboat Previous Member

    sure thing tunnels- Ill have to do some tinkering on the cad model but ill see what i can do for cross section views-- its really late here right now--but i wanted to come on and say that your water ballast idea is a good one. I think i'll add that feature in... easy to do and easy to dynamically lower and raise the waterline.

    Ok so the thrust- the engines have thrust bearings... the engines are directly coupled to the shaft at a 1:1 ratio producing about 500 rpms..the thrust from the shaft to the engine is absorbed by long, longitudinal engine bearers, that run 1/2 the length of the boat made up from scrap core and epoxy bonded into place.then wood bearers are screwed and glued onto those stiffeners. in a type of box formation so the bearers and engine mounts end up being structural. there is also reinforcement and insulaiton where the boiler will sit which is directly under the steam stack and in between the two engines. I do apologize since i gave you a pic of my single screw- in reality it will have two engines with a 7 degree offset for the shaft.
    see attached... the shafts will be supported by struts and shaft logs -the sleeveless cutlass bearings inserted into the shaft. there will likely not be keel shoes, but i may add two keels for directional stability and to protect the props so shoes could easily be epoxy joined to the deadwoods.
    the steering is NOT hydraulic--it is edson pull pull type..easy simple and effective. requiring only one steering quadrant. the two rudder shafts are set in place using a collar tie for each but do not come to deck level. the collar ties come to just below deck level and a stuffing boxes rudder tubes, for the rudders are welded in with epoxy as mentioned.
    A steering rudder with a tiller arm is stowed away and if needed placed into two eye sockets at the stern in case of rudder failure. yes also the aft engine trunk is removable with bolts as is the wheelhouse in the event of needing to be moved or engine replacement. there are two flush deck access hatches
    one in the stern quarter and one f'wrd. i'll try to get you those cross sections...therte isnt much room between the deck and bottom at the stern about 18 inches or 450 mm.

    Attached Files:

  6. tunnels

    tunnels Previous Member

    Please excuse me but the best impression i can think of its cute !!
    Looks like could be called "Prudence" :eek: i wiki'd and this is what i found ! Prudence as the "Father" of all virtues!! not bad !!
  7. tugboat

    tugboat Previous Member

    ;)nice name--the name ive given him is "el kapitaan" after the mountain...i hope if i ever insure it--the underwriters will think its cute too!..ABS needs something for tugs..btw came across this...http://www.scrutonmarine.com/W2244.htm

    u.s. navy built--frp/grp!!! 1/2 inch thick...still going! 450 hp 6-71 t.

    but i digress-where to look for |Lloyds and Abs for my "cute" little tug...ugh
  8. tunnels

    tunnels Previous Member

    Glass thickness . the 90 footer we just done has a solid glass bottom and is 18mm thick !!
    the 147 foor super yacht i was a part of had a solid glass bottom and was 15 mm thick the 48 foot cruisers we make are 9 mm thick the 28 foot is just 6 mm The 90 foot we used 25 mm balsa core as the bulwarks are 500 mm high with outer and inner the inner has a 3mm core mat layer , the 147 had 50mm H80 Divinicell corein the topsides and 6mm glass each side , the 48 footer also has 3mm core matt in the topside and 4 mm glass outside and inside . !
  9. tunnels

    tunnels Previous Member

    Saying a boat has a 12mm thickness looks impressive but really is not that important the same amout of strength can be achieved with a thinner laminate simply by using better glass materials so dont get hooked on having a superthick hull or what ever . The laminate stack is really important and dictates its stength and how good it will stand up . cores will give thickness and thickness without lots of weight . the thickness also make the panels more ridged so they will hold there shape better and you are able to use far less bracing every where . the use of core and shape you can almost completely do away with bracing !!. .
    if the right glass is used and panels move a little with flex and twist it makes panels much more durable !! flex can absorb and repel loads with out damage .thick cores can be used in places where you dont want much movment and thinner cores will allow movement but the glass can remain the same in both panels only thing that changes is the core thickness .
    understanding what the differant materials can do and what they will withstand is what is important .
    I said your hull could be made of chopped strand and woven roving
    Woven is impossible to shear within its self so using vinylester resin which is much stronger than polyester you can make a very strong robust and durable hull !! Its very doubtfull you will get shock loads as shock is associated with speed and pounding and crashing into and through waves .
    Chopped strand layers can be used to form a solid glass core like layup with woven each side .

    In the boats we make this is the principle i use but we use a stitch material because it uses less resin and saves weight .
    In your boat you dont want stitched fabrics because of the possabilities of shear within the layers of glass that make up the fabrics.

    This is probably as clear as mud !! anyway thats just the begining !!:p
  10. tugboat

    tugboat Previous Member

    Tunnels --so you are saying go with woven roving and mat?..that works for me -its cheaper! by half. but please explain--how would stitched fabrics shear within the layers of glass? do you mean buckling shear? or core shear?
    pls elaborate?
  11. tunnels

    tunnels Previous Member

    Ok basics
    Woven is imposible to shear within its self it can shear off the surface it stauck to that is why you always have chopped strand matt between layers the chopped strand acts as a glass reinforcement to the resin and gets a really good hold .
    With stitched materials the layers of glass and simply laid one ontop of the other and there just glass to glass the stitching hold the layers together but its reall the resin thats doing 99.9% of the work so even if it has a chopped strand layer each side of the fabric there is just resin abd the stitching to hold the layers together be it double bias or 0/90 there 2 layers , triaxle 3 layers quad 4 layers and no csm to hold each of the layers together its just the strength of the resin and the sewn thread . ita sticks ok to the surface it laid on because it has scm between . its possible the layers within the fabric shear so more layers the more likely to shear .

    Core shere is something differant . the core can adhere to the glass without any problems the the core will shear within its self !! in recent times foams have improved a lot the density of the foam core is very important is better to up the specs and never down the specs .Core cell seems to be the best of them all !!. Yes there has been lots of it used and myself have laid lots and lots but for a work boat like you making if you insisted on foam then decrease the thickness and up the density and have more areas divied in to actual panels with glass to glass skins coming together 60 to 80 mm wide around all 4 sides . so is if for any reason a panel shears then it will only shear to the glass to glass edges and very unlikly will travel from there .

    Balsa on the other hand i have never in all the time i been in glass seen it shear or even break in any way what so ever . Yes foam will distriute a blow to one surface and not transfer to the other side but then you going to get a weak place and a place where shear will start from the sellers will never tell you that .
    Some where here in Baot desibg i have some close up photos i posted a while back its really interesting to see the structures of materials in close up .

    Then theres peel this is really scarystuff !! if an object penetrates a outer skin and digs into the core then you get peel !!, with a foam core you will be amazed at how easy it peels apart and outer and inner skins separate but Balsa in the other hand is completely the opposite and will deflect the object away from the balsa and make it slide along the outside glass layer .

    During my coloured past and many differant jobs i've had i did glass repair work and this is where you see in glorious detail what works and what dosent . the distruction of things is amazing how they tear apart and get distroyed when just a few feet away theres vertually no damage at all . But why ?? I spent many hours disecting and working out the reasoning for these things happening . a very high percentage was simple bad worlmanship and bad work practises , the rest was poor choice of materials for the job

    I happen to be in the right place at the right time when the YOUNG AMERICA BOAT THAT BROKE in half during one of the americas cup races in New Zealand !! he boat very hasterly ended up in a part of the workshop in the company i was working at the time ! We were not able to get into see what was going during the cut and dispose of the dammaged are but once the curtans were lifted and all the damaged Carbon parts were tossed out side i was all over it like a rash . the carbon unis had vertually no resin and you could strip the fibres apart very easy there were even places where there was no fibres touching the other layer below , but with the combination of poor design and poor materials in just one part right in the middle and it got loaded beyond it capabilities so it broke . The repair and the modifications were all done and it went back into the water in quite a short time . Structures were finshed abruptly and nothing to distribute the enormous loading from that point onwards . really bad designing thats for sure . the changes and new modificationd all made sense couldnt get any photos, but i still have some chunks of the boat in a box in storage !!.
  12. tugboat

    tugboat Previous Member

    Tunnels --thats simply incredible that you were able to figure so much out where you were working-- you have wayyyyyyy more experience than I when it comes to knowing how to do it properly...but the problem is Vinylester resin is so expensive..in fact its almost as much as epoxy in these parts..id rather go epoxy. since the difference in price doesnt justify buying vinylester. I think Isotropic might be ok too...

    so a single laminate is better below the hull?--after all this is what the designer calls for...i dont have the laminate schedule with me here--but i will post it later -and let me tell you- it is heavy duty!..7 or 8 layers of both csm and mat. what about sweating?? i.e. like steel, doesnt a single layer of frp sweat??
    I have a quote from noahs marine on wovens though, and why to use a knitted over a woven: http://www.noahsmarine.com/images/2007catalog.pdf

    sorry that i could copy and paste the info but open this up and go to page 40 in pdf.. there is an argument there for using knitted fabrics..over woven...
    they say something about the fatigue of the material over time...compared to knitted which does not shear within the laminate...

    check it out..

    btw thanks for all that info--i really have to sit down now and think about all that you said because there are so many choices and decision to be made this way... now i am back to wondering if steel is the better route...since i can weld easily..but the extra costs and maintenance are a bugaboo!! so glass fiber/resin seems like a better alternative...im not keen on having to buy all that lfiting equipment for one job and special tools that add into the thousands...
  13. tunnels

    tunnels Previous Member

    yeah looked at the pdf theres a 18 oz and a 24 oz roving !! 24 takes lots to wet ot out specially using epoxy . so id sway towards 18 oz wr . i saw the discription and must sit and read later . the differance with epoxy and vinlyester ! vinylester is much easyer to use and lots quicker at some time down the track yo can use polyester on top . but if you start with epoxy you have to stay with it forever !! poly or vinyl dont stick very well over the top epoxy over the top of the other two OK
    Do you get the gist of the strand oriantaion 0/90 ? 45/45 ? 0/45/45 or
    90/45/45 ?? both of the last two are triaxles just the strand on one run length wise and the other they run across . They both have there uses and it possible to use one in one part of a hull and the other right along side in another part of the hull !!! because they have strength rinning at differant angles !!
    Laying glass id best to do long runs as much as possible rather then short lengths and lots of over laps . So when you looking at widths check carefully can get a wide fabric that covers a bigger area in just one pass or use narrower and lay 3 rows and use the overlaps as a strengtheners bit like a stringer so the glass is doubled up in about the same place each time !
    We use this method with yachts construction a lot in the old days!! now no one even thinks anymore they just do and move on !!
    The big boat we just done i found some extra wide fabrics that were 0/90 plus a 275 gram of chopped strand matt attached , The rolls were 2.4 wide which was perfect for what were were doing and cut out one row of longtudinal joins each side . the guys did not realise what they were actually doing but it covered really quickly and again the job was done in far less hours than if we'd use the standard with roll !
    So check widths of the glass and see whats the best way to lay from the top down or the bottom up . overlaps specially in thick lay ups need to be staggered at least a foot apart so you dont get really great thick patchs but again kept close they give a stringer patch that you can use to good effect . oh yes theres more to laying glass then first meets the eye !!
    You can get rove matt which is a woven roving with a 225 gram chopped strand attached (sown on ) again its saves handeling another layer of glass because its 2 layers in 1 !!
    Time spent sorting is well spent and saves some hard work later on plus its interesting !!
    Usually when i get a set of plans i sit with a tape measure and draw out sizes and then work out which is the quickest and best way of doing the job Always the guys dont understand why they have to do each layer diffrent from the one before ! most are not to bright including there boss but hes an expert so i was told !!.
    I haven t mentioned unidirectionall as yet because thats something else and takes some thinking about to get the best use from them !! later !!
  14. tunnels

    tunnels Previous Member

    Ok heres some brain teaseing for you all !!
    You have a look at the great long lists of glass and what do you see ! seems like some things are repeated untill you have a much closer look !,
    Woven roving the only changes are the weights of glass thats about the lot 18 0z 24 oz used to see 36 oz and very rarely 48 oz the only thing thats changed is the addition of a chopped strand on one side !! the courser the weave the heavyer the chopped strand should be . why? because the weave is so big and take so much resin just to wet the glass and then theres all the hollows between the weave that hold loads of just resin so the chopped strand is there as a bed to glass to get into and reinforce those patchs of resin . Make sense !!

    Now we have 0/90 which is stiched it also comes in Various weights but because the strands lay ontop of each other not woven its rolled and flatterned so is not as thick and bulky with far less space for voids and places to get just resin , The layers of strands are flat so are closer together so uses less resin to wet it out . Also its availible with a stitched on Chopped strand matt on one side ,usually 225 to 275 gram AND the chopped strand has no binder !!

    Theres also 45/45 double bias its just two layers and lays nicely and works well almost any where . Comes plain or with a chopped strand stitched on one side . double bias is good to use is most any where ,specially if a panel has a bit of movment and takes loads ,will give a little more flex thats not a bad thing , if a panel has some flex will take more to actually break it so is a little more durable !!. Used in conjunction with a core it makes good panels such as cabinsides ,cabin roof and the like ,it goes round corners and over shapes reasonable good as well .

    Ok now Triaxle !!
    So far i found 0/45/45 , 90/45/45 , 45/90/45 , 60/90/60 !! wow this is confusing !!
    The first 0/45/45 makes sence and could be used in the bottom of a hull in a powerboat Just as a example 0 would be to the outside 45/45 towards the inside! Now we have 90/45/45 this i would use in the topsides with the 90 running vertical on the outside of the laminater and swapped to the 90 as the outer layer on the inside .
    The placement of the differant layers adds stiffness and makes the sides of the hull stiffer! any of this making sence ??
    The other two also have the same effect but the last one 60/90/60 would be my choice as the stiffest of them all !!
    Top side panel of a hull ususally get pushed inwards so a choice of 90/45/45 for the outer skin and then the middle layers possibly with a core and then the 60/90/60 for the finished layer inside
    Bridging over a join strips of all the triaxle are much better than using any woven roving like has been used in every place i ever worked in and still is used . Just 50% of the woven is actually holding the join together where as double bias and all the triaxles 100% of the glass is holding the join in place .
    BUT if you have understood what i have written you can cut the woven on a 45degree angle and then it becomes a double bias woven roving and thats even better !! Cut on a angle its terrible stuff to try and use and falls to pieces and loose strand falling every where !!

    Simply by flipping a layer Of triaxle and placing the strands in a differant order within a laminate stack can noticeably add to or decrease the panels stiffness
    In the case of wanting better durability from your glass burying the main longtudinal layers that do a major job protects it !! buried glass is much stronger and lots more durable than having main layers close to or at surface level just behind the gel coat !!

    Are you following all this ??

    Then we get to Quad 4 layer!! will give a good constant thickness of glass running in 4 directions ,so is good for all maner of things
    In the power boat we been making i have changer the layup and we now use 2 quads layers (one inner and one outer ) of over 1200 gram each , took the woven out completely plus taken some of the chopped strand matt out as well !!, but over all the glass weight has still remained the same but now we use less resin !!
    For making our decks took out the woven and replaced with a doble bias for the outer layer and as the inside laminate used the quad , its really good . its easy to use take a little longer to wet out and soak but the whole job is tidyer and more consistant in thickness . :D

    I made 2 samples 20mm wide x 300 long of a piece of 0/90 . when it was hard and cured i gave the two samples to the guys in the shop i marked top on each one one ,up one way and one up the other but they were identical . aske which one was the strongers every one said the one with the stand running long ways along the top so i turned them over and asked again they then said the other one was stronger The asked why ?? no one could understand that just becasue the layers of strands were in a differant place within the sample it made so much differance .
    Try it some time !! make samples of some differant glasses but all the same size and when they hard do some bending and then flip each one over and notice if theres any differance .
    Its not very scientific to some of our learned friend but to us common low lander folks down on the factory floor its interesting and worth remembering how to get just that little more from the same materials we use every day that we never ever think about !!

    One last thing i forgot to mention is with some of the glass fabric during there manufacture the bundles of strand ar not all the same weight !! take a triaxle the 45/45 could be a sightly lighter weigh glass than the 0 which is a heavyer glass !!,so like i pointed out that then becomes the main layer that needs to be protected in a robust ,durable lay up .
    I did some work on Progressive distruction of glass layups longtime ago , this was all to do with life saving equipment manufacture for exstreme conditions !! boy was that a interesting subject !! tough and all as carbon is it was one of the lowest rated !!, highest was Kevlar naturally but just ordinary, every day ,,run of the mill, glass off the shelf was pretty close behind !
    So strongest is not nessasarily the tuffest
    Hope im note boring anyone with all this !!:eek::p

  15. tugboat

    tugboat Previous Member

    Thats awesome--you need to write a book about this...theres so much info its going to take me a day to digest it!
    so you are saying quadraxial is the best..followed by triax etc...and that cf isnt as good as the kevlar and typical e-glass runs a close second?
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