outboard set up

[doggy39]

Just wondering if some one can help i have a seajay 4.35 sp with a 40hp mercury 2001 gas assist ,i am having problems getting it to ride propley with a se sport 300 hydrofoil it jumps out of the hole great but rides nose down to much with a bit of speed have taken hydrofoil off and now taking off bow lift is terrible until it gets going , i have had the motor level with bottom of hull would it help to drop the motor down as far as it goes , cavitation is not a problem until i trim it out another hole .

Doggy39

[finga]

Welcome to Ausfish matey
A picture would help.
There's been lots of threads with motor height. Go back through and have a gander. There'll be more then just motor height info.
Personally, I like motors up about 1-1.5 inches above bottom of the hull especially with a foil but a picture would be helpful.
If the foils in the water whilst planning it'll cause nothing but heartache.
Cheers Scott

[doggy39]

Thanks Scott will have a play with that motor height

[FNQCairns]

Doggy39 My crystal ball says you are probably over proped and are chasing your tail finding a patch, the right prop will see you over the hump onto the plane nice and fast and at speed will give enough bow lift due to reduced slip to allow you to choose a better permanent trim setting, which by the way will always be a trade off to some extent without trim/tilt.

IMO a person can never go wrong raising the engine to suck it and see as the first step though.

Forget the foil they are crap, up, down, left and right!

cheers fnq

[wiz]

Hi Doggy39

I have a seajay magnum 4.15 with a 40hp yammie I had the same problem with scary nose up attitude on take off. I thought it was because I had max hp on small boat. once on the plane very happy with the ride for a tinny.Mine is a manual trim also and tried different trim without success. Have put 2 kids and adult up front and boat still stands on its bum until on plane. Interesting to hear you have same problem with larger and heavier boat.
Surely its not hull design???????
Or is the 40hp to heavy for these boats???
I put a SE200 on my motor because I wanted to get on the plane quicker but not change the ride to much.(ie bum lift to much)
What it did was stop the nose up problem on take off but the boat does seem to sit flat at speed without the nose slightly raised.
Trimming out one hole causes to much cavitation.
the cav plate is level with keel.
Is the merc & yam prop the same ??????? mine is a 11 3/8 x 12
surely the merc supplier and yam supplier would not both install the motor incorrectly??????(ie motor height wrong)

would be interesting to hear what you guys can suggest


Cheers Dan

[finga]

You might be right there FNQ when I think deeper into it.
When you say it has terrible bow lift until it gets going without the foil what's it like after it's going??
When you say it sits too low in the nose when it's going with a foil what does it do that's a problem?? Is there spray or does it nose dive or...??
A few other indicators needed as some say my tiny tinny sits too flat whilst planning but it suits me just fine and has adverse side effects.

[bushbeachboy]

One of my previous boats was a Sea Jay 4.35 SP with 40 Yammie, manual everything. I found it to be a really good match to the hull, and the Merc should be very similar. I found that it did have a bow-up attitude to start with, but I was able to overcome that by being less gentle on the throttle, ie: to get it planing, give it full throttle for a few seconds, then back off to whatever speed/revs is good for you. The prop was standard Yammy, and I couldn't tell you what the diameter and pitch were, but they were a good match.

I would advise moving your trim pin 'in' one hole first, then testing. It's easily altered whilst on the water if you want to try different settings, just don't drop it!

Don't know about the foil on that hull, mine didn't need it. On the other hand a mate with a 4.15 Magnum/30 Yammy rig put an SE Sport 200 on his and it made it a better boat.

[Dan5]

Went for a spin on sunday in a brand new sea jay 415 territory with 40hp 4strk suzi it does exactly what wiz said ,it has power trim/tilt i told my mate to trim right in when we take off and to nail it and that will stop that stuck in the hole situation,so he tried what i said but nothing changed at all.We are going to look at it a bit more during the week so will keep you posted on what we can work out to fix his problem also.

[doggy39]

Hi Doggy39

I have a seajay magnum 4.15 with a 40hp yammie I had the same problem with scary nose up attitude on take off. I thought it was because I had max hp on small boat. once on the plane very happy with the ride for a tinny.Mine is a manual trim also and tried different trim without success. Have put 2 kids and adult up front and boat still stands on its bum until on plane. Interesting to hear you have same problem with larger and heavier boat.
Surely its not hull design???????
Or is the 40hp to heavy for these boats???
I put a SE200 on my motor because I wanted to get on the plane quicker but not change the ride to much.(ie bum lift to much)
What it did was stop the nose up problem on take off but the boat does seem to sit flat at speed without the nose slightly raised.
Trimming out one hole causes to much cavitation.
the cav plate is level with keel.
Is the merc & yam prop the same ??????? mine is a 11 3/8 x 12
surely the merc supplier and yam supplier would not both install the motor incorrectly??????(ie motor height wrong)

would be interesting to hear what you guys can suggest


Cheers Dan

Wiz my prop is a stainless vengeance 10 3/8 14 pitch

[doggy39]

it is just where the water is coming from the front of the hull like the boating is pushing thru the water

[wiz]

doggy 39

my boat also feels like it is pushing water also. I dont think mine would be as bad as yours because of the difference in surface area of the SE200 as to the SE300
Surely buying a 4m tinny with a 40hp motor should not require all this stuffing around to get it to work properly??????? without foil take off is scary
I went for the 40 because I would not have to run it at wot to get a decent speed therefore longer life of motor.

this is starting to look like a hull design problem to me as it is the thing that is common in the three examples. maybe the rating should be lowered?????????

anybody else got any ideas????????

cheers dan