Hull Cornering Characteristics

[NZjohnson90]

I have been trying for a while to find something on cornering characteristics of different hull types but cant seem to find a single thing.

I have touched in this subject in a previous post but I thought I'd try again to be a bit more specific.

I recently put my boat on the water for the first time after a year of tinkering with it, although it had a few teething troubles which I have now hopefully fixed, all went well. and it should be back out for test run number 2 this week.

The only thing I have not got to the bottom of yet is the cornering, maybe it's fine and nothing is wrong I am just trying to get some advice.

The worry I have is that it just doesn't lean/list/bank (or whatever the correct term is) into the corners at all - whatsoever. It feels relatively solid in the water, stable, doesn't bounce (if it's flattish water), turns tight enough, prop doesn't ventilate or anything. But it just feels somehow dangerous to turn that flat going at high speed, it feels as though if you hit a wake or chop turning anything but real wide going at any speed it could flip.

My family had small ski boats when i was growing up, first we had a 14ft bry-owen with a very similar v hull to my current gastron and from memory that did bank into the corners and you could turn a tight corner at speed. Then they had a Delta 60's two seater inboard race/ski boat that was completely flat bottomed with fins on the bottom, and cornered totally flat like my glastron does now but was super precise and could turn a corner virtually in it's own length at any speed ( you could actually get it to spin 360 at vertually full throttle) my boat does not feel anything like that stable.

I will put up some pics of the hull so you can see what type it is but the boat is 14ft and has a Johnson V4 90hp, which in hindsight is probably a bit over powered but I doubt that would change the cornering??? The believe the engine is mounted correctly after reading many threads on the subject on here. The only things that I could think of that might have an affect are 1. the weight distribution (for and aft) as at the time the boat was very bow light, since then I have altered that by moving batteries fuel and adding a sandbag or 2 so hopefully that should now be good. and 2 weight distribution (port/Starboard) I moved the seats out to a wider position just to give a bit more room in the cockpit, and to line them up better with the steering and controls as they were originally very much in the middle of the boat - I cant see that a few inches makes that much difference but maybe???

Sorry I have probably waffled on a bit here but what I am after is a general run down of what different hulls handle like - tri hulls - flat bottom - deep V - hard chine - soft chine or whatever.

Any help appreciated so I can either feel safer as it is next weekend, or fix what needs to be fixed before it goes out

http://i497.photobucket.com/albums/rr333/kiwigt/IMG_1221.jpg
http://i497.photobucket.com/albums/rr333/kiwigt/IMG_1224.jpg
http://i497.photobucket.com/albums/rr333/kiwigt/IMG_1227.jpg
http://i497.photobucket.com/albums/rr333/kiwigt/Boat/IMG_1935.jpg

 

[NZjohnson90]

Re: Hull Cornering Characteristics

Sorry bout the huge pics - not very computer literate and dont know how to resize....

 

[marine4003]

Re: Hull Cornering Characteristics

Deadrise...the more you have the better she corners. Thats why Offshore racing boats and public use performance boats have "deep vee" hulls, if theres not enough the hull wont "grab" on corners.

 

[oops!]

Re: Hull Cornering Characteristics

hi ....you are way over powered.....that boat is more likely a 60 hp.....

but as far as the handling......yor boat is more flat than not, that means...little "roll" also it looks like is has an aggressive chine.....that will grip the water in turns......but the only way to tell, is find a similar bottom boat and test it!

 

[itsaboattime]

Re: Hull Cornering Characteristics

As stated above........you are over powered. Your boat doesn't sit low enough in the water to bank. My advice, ummm slow down to turn, more hull in the water = better turning.

I may be wrong but that is way it seems to me

 

[Philster]

Re: Hull Cornering Characteristics

Nothing to pivot on.

The flat-ish and wide-ish part of the hull is keeping the boat flat, sort of like a low, flat car chassis.

I wouldn't expect it to dig/roll into a turn. The onlt V is up front.

Not really made for zipping around turns like a performance boat.

 

[tashasdaddy]

Re: Hull Cornering Characteristics

suggest you take a safe boating class, all this is covered.

 

[NZjohnson90]

Re: Hull Cornering Characteristics

Thanks guys, thought that might be the case, guess I should just go very easy cornering in any kind of chop.

I know the boat is overpowered - i bought the motor not really realising how big it was - on the advice of others, and 1 day maybe I'll upgrade the hull, I want to keep the motor, both because it seems very sound, and It's probably the smallest motor that could pull me out of the water without much effort for skiing I am 110KG.

For a halfway decent hull here in New Zealand it seems you are looking at $2000+ which is a lot of cash to me so until then I will just have to go easy with the throttle. I just want a boat that is cheap, but has enough grunt to pull me out of the water.

I'm not a boy racer, don't give the boat full throttle at any time, and i dont turn like a lunatic. I just wanted to feel safe so thats why I asked.

I did do the RYA powerboat course but it didn't mention very much at all about hull design.

Oh.... and what is deadrise.?

 

[Willyclay]

Re: Hull Cornering Characteristics

Oh.... and what is deadrise.?

http://www.answers.com/topic/deadrise

 

[Chris1956]

Re: Hull Cornering Characteristics

I was unable to see the pictures, however, normally a 14 footer will have 40-50HP max on it. Hulls will handle differently at different speeds. Even a vee hull will slide around corners, if you are going fast enough. Flat bottom boats slide around corners at most planing speeds. We had a flat bottom wooden rowboat that slid around corners, while powered by a 9.8HP Merc.

My vee hull speedboat slides thru the corners at 50MPH or more, and banks nicely at lower speeds. Normally, the sliding won't cause you to flip, although it can be unnerving.

 

[NZjohnson90]

Re: Hull Cornering Characteristics

Thanks for the article willyclay, I am slowly learning more each day.

Chris the boat does not feel like it's sliding at all around the corners. It does feel very solid, like it has a good grip in the water, it was just the angle of the boat that worried me at higher speeds.

From what everyone is saying it sounds like that is just the hull design i am not used to. I'll just take it easy till I get a good feel for the boat, and not hoon around too fast. I guess it only has as many horses as I give it throttle.

 

[Frank Acampora]

Re: Hull Cornering Characteristics

Your hull is a shallow Vee design with not much "Deadrise." Deadrise is the amount the outer edges of the hull are higher than the center of the vee. That coupled with the very large reverse chine (turn down at the outer edges) will make it grab the water without leaning too much in turns.

Now: As to power. Yes, that hull would most likely be rated for somewhere around 60 maybe even as high as 75 horsepower since it looks wide at the transom. HOWEVER: If you are comfortable with the extra horsepower and the boat does not have adverse handling with it, and NZ does not have max HP laws, so local water police will fine you, AND if you are not worried about getting sued in case of an accident, KEEP the big engine.

Did I understand that that hull is a Glastron? If so, what year? It would look like an early model.

 

[NZjohnson90]

Re: Hull Cornering Characteristics

Your hull is a shallow Vee design with not much "Deadrise." Deadrise is the amount the outer edges of the hull are higher than the center of the vee. That coupled with the very large reverse chine (turn down at the outer edges) will make it grab the water without leaning too much in turns.

Now: As to power. Yes, that hull would most likely be rated for somewhere around 60 maybe even as high as 75 horsepower since it looks wide at the transom. HOWEVER: If you are comfortable with the extra horsepower and the boat does not have adverse handling with it, and NZ does not have max HP laws, so local water police will fine you, AND if you are not worried about getting sued in case of an accident, KEEP the big engine.

Did I understand that that hull is a Glastron? If so, what year? It would look like an early model.

Thanks for the info on the hull Frank I thought that was gonna be the case but just wanted to put myself at ease. NZ does not seem to have any laws regarding max HP etc or hull HP ratings. It is currently insured through Club Marine and they said nothing about the size of motor for the boat, they did want to see a picture though but did not question it when they saw it. As I said before I just want the horses to pull me out of the water, not for hooning the boat around at dangerous speeds.

As for the Hull It has Glastron Badges on the back, and had Glastron Logo on the dash but this had to go as it was falling to bits. I have seen quite a few of these hulls for Sale around NZ, so must have been popular in the 70's? Many of them also seem to be branded Glastron, However I have also seen the very same Hull (with slight differences) for sale branded Glasscraft, Gullwing, Glidecraft and other things. Some have different screens, some have a small cabin, different seets, different dash layout, but all without doubt the same Hull.

My Hull has no plates/ID's/Serial Numbers, nothing. So I dont know it's history whatsoever. If anyone else does I would be interested to know. I guess it was some sort of universal Hull mold that several companies used and I would guess that my boat was made by someone else under licence from Glastron in NZ rather than a US Glastron import????

Here are a couple of other same design hulls for sale right now.

http://www.trademe.co.nz/Browse/Listing.aspx?id=262313475
http://www.trademe.co.nz/Browse/Listing.aspx?id=262406290