tinny speeds

[Zim man]

Hi all

i am going out this weekend to play around with the motor on my tinny and try and get the best performance from here.

Previously i had been struggling to get her to plane and soon found that a part had come off in the motor which was soon rectified (it just clipped back on). I instantly had 5 times more power yet it struggled to get on the plane with 3 people on board (weight 260kg)plus fuel, batterys and esky. some people i have spoken to have said that my tinny should plane easily with this weight whilst others have said that i was pushing the rig to its limits. i am not looking for top speeds but rather a boat that can get on the plane quickly as opposed to ploughing like a farmer.

My tinny is a 4 metre hornet widebody with a 25 yamaha. The motor starts first time everytime. the prop on it is a 9 7/8 x 11 1/4. Maybe its a prop issue to get on the plane. A member on here who has been most helpful suggested a 10 x 11 as it works for him.

Anyway i am heading out this weekend to play around with it and try different set ups and would like to know what you think i should be doing in the rig. i will have a GPS with me this weekend so i can measure the speed.

Also is it better to have the weight upfront or at the back of the boat. I grew up with fibreglass bass boats and we always put the weight at the back. not sure how it goes with tinnies.

cheers

rob

[dassa]

Hi Rob before you change your prop try by putting sting rays I think there call on your motor they help get it up on the plain alot easer.

cheers dassa

[bigtez]

You should be able to get 40kph+ and still get out of the hole promptly with that setup. I would start by moving some weight around. Assuming its a tiller steer, then a fair proportion of the weight will always be at the back of the boat. If you can move some forward and trial it, don't forget you may need to change the trim as well.

If you can Rob, post up some pics of the motor height compared to the keel. You may find the motor is a bit too low.

Personally I would avoid spending any money on props etc until you get the weight and motor height right, they are free to change mostly.

Terry

[nadders]

weight should be at the front and motor trimmed as far down as possible to get it on the plane then trim it up a bit (if you have power trim) once there for better economy and speed

otherwise the hydrofoils that bolt onto your stock cavitation plate might work for you as they give lift to the back of the boat similar to an aircrafts wings but i was advised against these unless really needed as they can be hazardous in heavy following seas

[noname]

25 hp and 4 mtr tinnie, well i believe they don't go to well together. a 30 or 40 to be precise would be better, but hey. def get a stingray. and get that brand, don't skimp here as that brand worx very well. start off by like some 1 said with ya motor tucked all the way in, and slowly trim it out until you find a happy medium, when trimmed at different positions the torque of the motor will be different at trim settings too, so be aware, and take a spanner to adjust the trim tab at the cav plate! and also as somee1 said weight forward. if your alone in it, but constantly movin weight in tinnies. nature of the beasts.

rob

[buzzid]

25hp on a 4m tinny is quite sufficient in my opinion, unless you intend to go racing. i have a 25hp 4 stroke on my 4m v nose punt and it gets me to fishing spots on time. just recently i took family members from overseas for a ride from brekky creek to toowong on the the brissy. 4 adults, 2 at front and myself and another at the back and a 25 kg dog in the middle(yep grossly overloaded i know), took a little longer to get out of the hole but never did it not look like getting up. once on the plane top speed was only a little down on its speed with just me and the dog, which is around 48kmh. admittedly its a new school injected merc but also on board is a 17mm ply floor and forward casting deck, 20ltrs of juice and 2 batteries. i would look at your set up with motor heights and trims and as others have said don't rush into buying a foil till you can get it going a lot better, you will only be disappointed, as i have been in the past. i've always been of the belief that all boats and motors work fine as they are without having to drill holes in things to bolt on a pair of wings provided they are correctly set up with an adequate power to weight ratio(which i believe you have).

if people where meant to fly they would have wings.

good luck with it all mate, the blokes at holt marine have helped me heaps in the past with the same issues.

buzz...

[noname]

your knowledge of boats shows here buzzid or whoever you are, you could put a 9.9 on a hull like yours and it would still be fine, you have to understand that all hulls are not created equally! flat bottom boats or punt style boats need no horsepower to get them planing, but maybe you can fill in for all us dummies how the concept of different hulls actually work.

rob

[buzzid]

mate there is not one mention of the word hull in my post, nor is there a claim of knowing all, however there is mention of what i currently have and a reference to this not being all i've had. take it easy tiger.

buzz

jamie martin

[Travis]

buzzid wrote:

25hp on a 4m tinny is quite sufficient in my opinion, unless you intend to go racing. i have a 25hp 4 stroke on my 4m v nose punt and it gets me to fishing spots on time. just recently i took family members from overseas for a ride from brekky creek to toowong on the the brissy. 4 adults, 2 at front and myself and another at the back and a 25 kg dog in the middle(yep grossly overloaded i know), took a little longer to get out of the hole but never did it not look like getting up. once on the plane top speed was only a little down on its speed with just me and the dog, which is around 48kmh. admittedly its a new school injected merc but also on board is a 17mm ply floor and forward casting deck, 20ltrs of juice and 2 batteries. i would look at your set up with motor heights and trims and as others have said don't rush into buying a foil till you can get it going a lot better, you will only be disappointed, as i have been in the past. i've always been of the belief that all boats and motors work fine as they are without having to drill holes in things to bolt on a pair of wings provided they are correctly set up with an adequate power to weight ratio(which i believe you have).

if people where meant to fly they would have wings.

good luck with it all mate, the blokes at holt marine have helped me heaps in the past with the same issues.

buzz...

[noname]

buzzid wrote:

mate there is not one mention of the word hull in my post, nor is there a claim of knowing all, however there is mention of what i currently have and a reference to this not being all i've had. take it easy tiger.

buzz

jamie martin

i was just refering to your boat atm a 4 mtr v nose punt.

that rig would require no horsepower to get along, we don't know what sort of hull ol mate has. but i'm assuming if it won't get on the plane with a misfiring 25, it aint a punt style boat.

rob

so hard to compare your boat with ol mates boat.

[shortie]

I ecommend a 30ph or 40hp for a 4+mtr boat.

[bootyinblue]

Ol' mate quite clearly says his boat is a 4m hornet wide body.

I would say you need some more horses though. I have a 4.2m runabout which is essentially just a tinny with a steering wheel and have 40hp 3cyl Merc to push it along

[noname]

so it does sorry ppl, i think he might be in a spot of bother then.