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Thread: Planning strakes, has anyone added them?

  1. #1

    Planning strakes, has anyone added them?

    Hello All

    Has anyone added planning strakes to their boat and if so how has it changed things?

  2. #2

    Re: Planning strakes, has anyone added them?

    That is entirely dependent on the hull shape, some benefit, some don't.
    Jack.

  3. #3

    Re: Planning strakes, has anyone added them?

    Always wondered why ally boats dont have them and glass boats do?

    Sent from my SM-G900I using Ausfish mobile app

  4. #4
    Ausfish Platinum Member
    Join Date
    Mar 2015
    Location
    Kalbarri, WA

    Re: Planning strakes, has anyone added them?

    Strakes look simple, are not. They have a great effect on boats overall ride and handling. I've sometimes wondered why ally boat builders dont experiment with them--if you think about it, it's a lot easier to tack strakes onto an ally hull with diferent shaping , spacing and lengths. Keep experimenting. My conclusion was that they really don't give a rat's ar***, can't be bothered, just keep chucking their inferior riding boats at people who don't appreciate the difference. It should be possible to get the same ride with an ali hully as a glass one--only difference would be the noise factor , as ali will always transmit a bang more audibly, and it will always sound worse. In December, I went past a Quintrex 580 punching directly into a short, lumpy nasty sea, the sort we commonly get early morning here in summer after the wind has blown hard all night then abated for a few hours after sunrise. Apart from the fact I was doing 25 knots and he could only do about 14, with frequent throttle chops , I could hear his bangs over the noise of my 150 Merc amplified by my hardtop. .

    On a more serious note, fibreglass hull design is set in stone once the plug is built and the mould is constructed. Get it right, it's right for as long as the mould survives, which can be forever. Caribbean 's 2300 is built using the very same moulds for the hull that produced the 23ft Bertram, when they were the Australian builders. All you need to do it update the moulds for the cap. The Reefrunner had actual hull design changed in the 90's --the old offshore racer Bertram 20 had 1 degree taken off the deadrise at the transom, for easier planing and more stabilty at rest. Pressed sheet ali hulls are also moulded really--light sheets pressed into a predetermined shape and fitted together with extrusions for the keel, coamimg edges, etc. So their design doesn't change, until they change it. Think Quintrex/Millenium/Millenium Blade. Plate boats, on the other hand, can be built two ways. Yellowfin, I beleive from watching a video, sits all the hull plates in place, then drops in the frames and stitches it all up. I have seen some on here refer to it an an "inferior" method of plate hull construction. As long as the design shape is adhered to, and it is all kept aligned, there is nothing inferior about it . You actually need to invest more in equipment, which a large company like Telwater can do. I would assume that the "superior" form , in those opinions, is lofting--where, as in boatbuilding methods that go back through the ages, a keel is laid, then frames, then the hull cladding is fitted. This is still widely used, particularly for larger hulls. It ABSOLUTELY relies on the keel and frame staying in alignment--if they move at all during construction, either from physical force being applied, or "pulling" during welding, you end up with a lumpy or bent boat. It is very easy to get a smaller plate hull which is warped in one way or another.
    One serious design flaw which afflicts many of the smaller plateys around is just plain bad proportioning. Manufacturers build 16 footers with near 2m of beam. People want a "big" boat in a length that will fit in their garage. Then wonder why is pounds really hard. It is impossible to get a good shape transition between the bow entry and the planing area , just too short a distance betwen the bow and the transom. Add to this, the investment required to buy real plate forming machinery. There are subtleties of shape in a good glass hull that are very expensive to reproduce in an ali hull. Look at BC--just a single angle of deadrise, bow to stern. Such a compromise. As you get longer, 7 metres and over (IMO) , it starts to become possible, but expensive.

  5. #5

    Re: Planning strakes, has anyone added them?

    Good reason why small alloy boats will never be as good as fiberglas boats, its the weight. My 420 renegade is miles in front of the 481 quintrex i had 15years ago for ride ( after my efforts to get it right). But even so, i throttle back when its really choppy. Sure i can plough through but the water just pushes it around.. I suspect one of the reasons Barcrushers have a reasonable ride is that they have substantial weight, let alone a trick ballast, which adds weight.
    But even so, they cant compete with say a haines signature because its designed to cut through with a reasonable amount of weight. When an alloy boat will perform like a signature, i bet the hull shape will be similar and have similar weight.
    Having said that, you dont buy an alloy boat to be a signature substitute, you would buy the real deal, so an alloy boat will have different expectations. More room for your buck isnt going to give you the same performance.
    As for strakes add ons, you need to do a bit of R&D on a hull, computer analysis, water tank testing, seat of the bum testing and lots of models. Did i not mention experience in boat design majoring in strakes? My guess, buy a boat that does what you want it to do up front, forget the experimenting, your not the engineer here. Accept your boat has limitations and enjoy what you have. This aint one fix for amateurs.

  6. #6

    Re: Planning strakes, has anyone added them?

    It's often said that fibreglass boats ride better than Aluminium simply because of weight, it's not that simple, get a flat bottomed Aluminium boat and fill it with sand bags, it will still pound your spine to pulp, shape has more to do with ride than the material it's made out of, it's all needs to come together as a workable package, weight helps, but it's not the be all to end all.

  7. #7

    Re: Planning strakes, has anyone added them?

    Some do. A mate of mine was building and selling platey's before his knees gave out. Strakes will give lift but will also make the ride a little rougher.

  8. #8

    Re: Planning strakes, has anyone added them?

    Well, i should have said, assuming the hull is designed to give a smooth ride. No amount of weight is going to fix a banga. Agreed its not the be all and end all but face it, cheap alloy boats are light weights. As such there is only so much water it can push aside before the mass of water acts like a brick wall.
    Same boats, one alloy and one fiberglass is going to be around 2-300kg difference. The alloy wont be anything like the fiberglass. on water. You cant change the laws of physics.

  9. #9

    Re: Planning strakes, has anyone added them?

    It's not about changing the laws of physics, it's about compromise to make a marketable product, if ride is a product of weight, then let's say they built a Barcrusher with 15mm bottom, and added some concrete for added weight, it might ride like a dream, but would require twice the HP, a bigger trailer and tow vehicle over a "standard" one, would it sell? sure lightweight pressed tinnies are harsh, but, they have a market spot to fill, fibreglass boats are not always heavier than a well built similar sized custom plate boat, and all fibreglass boats don't ride better than all Aluminium boats, the ride in my old alloy cat was outstanding compared to ANY similar sized (and some bigger) glass boat, it's all about design and intended use.

  10. #10

    Re: Planning strakes, has anyone added them?

    Quote Originally Posted by Noelm View Post
    It's not about changing the laws of physics, it's about compromise to make a marketable product, if ride is a product of weight, then let's say they built a Barcrusher with 15mm bottom, and added some concrete for added weight, it might ride like a dream, but would require twice the HP, a bigger trailer and tow vehicle over a "standard" one, would it sell? sure lightweight pressed tinnies are harsh, but, they have a market spot to fill, fibreglass boats are not always heavier than a well built similar sized custom plate boat, and all fibreglass boats don't ride better than all Aluminium boats, the ride in my old alloy cat was outstanding compared to ANY similar sized (and some bigger) glass boat, it's all about design and intended use.
    Your example of barcrushers is pretty much an affermation of what i said, lol
    it is about the laws of physiscs. A heavier boat will hit the wall after the featherweight. But lets not get too carried away on a one dimensional arguement.

  11. #11

    Re: Planning strakes, has anyone added them?

    Quote Originally Posted by Andy56 View Post
    Good reason why small alloy boats will never be as good as fiberglas boats, its the weight. My 420 renegade is miles in front of the 481 quintrex i had 15years ago for ride ( after my efforts to get it right). But even so, i throttle back when its really choppy. Sure i can plough through but the water just pushes it around.. I suspect one of the reasons Barcrushers have a reasonable ride is that they have substantial weight, let alone a trick ballast, which adds weight.
    But even so, they cant compete with say a haines signature because its designed to cut through with a reasonable amount of weight. When an alloy boat will perform like a signature, i bet the hull shape will be similar and have similar weight.
    Having said that, you dont buy an alloy boat to be a signature substitute, you would buy the real deal, so an alloy boat will have different expectations. More room for your buck isnt going to give you the same performance.
    As for strakes add ons, you need to do a bit of R&D on a hull, computer analysis, water tank testing, seat of the bum testing and lots of models. Did i not mention experience in boat design majoring in strakes? My guess, buy a boat that does what you want it to do up front, forget the experimenting, your not the engineer here. Accept your boat has limitations and enjoy what you have. This aint one fix for amateurs.

    my alloy boat shits all over my old signature. Same size. There are plate boats out there that ride as good, if not better than glass. And yes, it has strakes

  12. #12

    Re: Planning strakes, has anyone added them?

    I took a strake off a plate alloy boat. It stopped porpoising, and was more stable underway. The strake was located quite close to the keel, extending 2/3 way to stern. Also made the ride a bit drier.

  13. #13

    Re: Planning strakes, has anyone added them?

    Quote Originally Posted by robothefisho View Post
    I took a strake off a plate alloy boat. It stopped porpoising, and was more stable underway. The strake was located quite close to the keel, extending 2/3 way to stern. Also made the ride a bit drier.

    My mate did the same.

  14. #14

    Re: Planning strakes, has anyone added them?

    Thanks robothefisho I think you the only person that has answered my actual question and not filled the tread up with rubbish.

    I presume you actually didnt need the lift

    Im looking at try to get more lift. I run a alloycat that I have added weight too so in a hope to get more lift out of the water I was thinking strakes rather than cupped props ??

  15. #15

    Re: Planning strakes, has anyone added them?

    cupped props giving lift- lol we went through that on your last post and you didn’t get it. Yeah just add strakes to the cat that will help(Insert sarcasm here) and is not an exact science that the designer never thought of... you can’t overload a boat and expect it to perform by cupping props or adding strakes mate.

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