Trim problem on new Futura with 20hp

[hymerbeliever]

First trip out yesterday on my new (smaller) Zodiac Futura - it's a MK1 3.5m with a 2003 20hp Mariner 2 stroke. It was a pig to get up on the plane even on the lowest setting: the bow just went up and my son and I had to move forwards and it would eventually go, though not always with ease or without stopping and trying again. It flew then at 28 knots.

Not terribly satisfactory. The boat has speed tubes and is rated to 23kw (30hp) but may be it's too heavy and I'm going to try my 15hp Mariner 2 stroke that I was going to sell. We tried trimming up but, as expected, that made it worse. Perhaps a doel / whale fin will help unless anyone has any other suggestions?

[Poly]

Originally Posted by hymerbeliever

We tried trimming up but, as expected, that made it worse.

and trimming down?

Can you get any more weight forward? e.g. fuel tank, bigger anchor/more chain, all you kit right at the bow? A tiller extension to let you move your weight forward?

[Landlockedpirate]

Something very wrong here, Futura Mk1 with a 20hp should jump onto the plane. The bow will go up at first and because of the design of the Futura (and the fact that its a relativly small boat witrh a big engine), it will go very high but immediately come down again. There is no way it should need a hydrafoil 2 up.

Was it all inflated to the correct pressure ? Is it a short shaft engine ? Does it have some huge non standard prop on it ? Is the engine running correctly.

The weight of the 25 V 15 should make no appreciable difference on a boat of that size.

[Fenlander]

>>>Something very wrong here

Agreed... from the perspective of any SIB.

>>>my son and I had to move forwards...

Were you both at the stern?

Is there any chance this is just how it feels compared to your previous Futura where with you both on the seat at the forward steering posn it would be a far more balanced outfit with flatter transition?

Once going 28kts is impressive!

[hymerbeliever]

Thanks chaps. My son was on the seat, which I'd slid forward to the rear end of the front alu floor section. It did have 25l of fuel at the back and I may move the tank under the seat but will have to change to a Yam tank. Would give more floor space too. It was trimmed right down towards the transom. Same problem when we swapped places.


I have had a 3.4m Quicksilver and 3.6m Yam with my 15hp tiller Mariner on the back and never experienced anything digging in quite like that, and once on the plane there only seemed to be 2 speeds fast and absurdly fast. I was only inflated to 225mb and I see 240 mb is recommended...not much different though.


One way of getting more weight up front is to take the mother-in-law but ......

[dogboy]

my mk1 futura needs plenty of weight placed forward to get the front down. I need to use a tiller extension and have my partner move forward, as well as the kit in the zodiac bag upfront to get it to level out. I am also trimmed trimmed fully in. (mine's rated to 20hp and I use a 10hp 4 stroke)

[jyasaki]

Throttle? Best to whack it wide open, let the nose climb, and then lighten up on the throttle as the stern climbs out. If you try and finesse it up, it takes forever.

jky

[MatFromPoland]

High top speed and problems to start on plane sometimes are common to too big pitch in current prop. If moving weight forward not helps you can check smaller pitch on prop.

2 adults on Honwave T38IE2 and BF20 works perfect when one be on the bow.
With 2 on rear tubes - be not able to plane (nose up)

[hymerbeliever]

I took the plunge and bought an SE SPORT 200 hydrofoil Sport Marine Technologies which completely solved the problem. It is a bit of a monster but very well made and the boat now pops onto the plane instantly.