Bow dropping

[Matk]

Hi
I have a YAM380s Ali floor suited with a 4 stroke 15hp yam.
Issue is, once I get on the plain and open the throttle the bow begins to drop and tries to steer off to the starboard side. Ive tried raising the outboard slightly although still approximately 1” below transom. I’m only managing around 16kts when on WOT. Outboard is set on pin hole No2 from the transom. Ive run out of ideas. Thanks. Mark

[Pikey Dave]

Originally Posted by Matk

Hi

I have a YAM380s Ali floor suited with a 4 stroke 15hp yam.

Issue is, once I get on the plain and open the throttle the bow begins to drop and tries to steer off to the starboard side. Ive tried raising the outboard slightly although still approximately 1” below transom. I’m only managing around 16kts when on WOT. Outboard is set on pin hole No2 from the transom. Ive run out of ideas. Thanks. Mark

16kn doesn’t sound way off the mark.
What’s your WOT rpm?
Prop pitch?
Trim tab setting?

[Matk]

Hi
Thanks for replying. My trim setting is on hole 2 from the transom, it did have a 10-1/4P prop but I have replaced it for a 9P yet to try,,, WOT is around 4900 with 10P prop.
I’m more concerned that the bow drop and pushes the water as it tries to throw me out at full throttle, Ive tried all the trim settings. Do I need to lift the outboard more so its inline with bottom of the transom?

[Pikey Dave]

Originally Posted by Matk

Hi
Thanks for replying. My trim setting is on hole 2 from the transom, it did have a 10-1/4P prop but I have replaced it for a 9P yet to try,,, WOT is around 4900 with 10P prop.
I’m more concerned that the bow drop and pushes the water as it tries to throw me out at full throttle, Ive tried all the trim settings. Do I need to lift the outboard more so its inline with bottom of the transom?

Possibly a silly question, but is the boat setup/inflated properly? Is the keel straight? Have you tried putting some weight on the port side (fuel tank?)

[Matk]

Hi, yes all setup correctly and keel straight. The fuel tank is located central aft and I sit in the port sponson. I’ve only had the boat out a couple of times since owning and always does it. Just doesn’t seem right. I’m also alone in the boat carrying only a few items.

[Max...]

I would not expect more than 16 kts from that outfit TBH, less if anything.

[Fenlander]

Do you have an image of the outfit so the outboard leg and transom show so anything odd might be obvious to us.

Your description of bow dropping and veering off sounds a lot like bow steer which is usually when there is too much weight forward. However with a heavy 4-stroke and yourself plus fuel at the stern it would on the face of it be the opposite.

SIBs are usually quite even tempered with the outboard dropped on the standard transom set height then trimmed in the middle pin position... distribute your weight evenly and off you go.

A pic that showed the prop plus the pitch markings might help too in case it's got something weird on it.

What are you using to determine the boat is properly inflated?

[Pikey Dave]

Originally Posted by Matk

Hi, yes all setup correctly and keel straight. The fuel tank is located central aft and I sit in the port sponson..

Hmmm! You’d normally sit on the Stbd side to counter the torque of the prop. Try changing sides.

[jeffstevens763@g]

My two pence speed is about spot on weight distribution is the key as said move helm position and the tank back opposite you, hole two is good but it might need hole three in you scenario.

[Steve509926]

When I first got my SD360 I also suffered the bow dropping from time to time, being a newbie I thought it was normal.
Highland Haggis spotted it and suggested I try changing the trim pin hole to the next one away from the transom (No 3), had to redistribute a bit of weight, but what a difference it made.

As Jeff has mentioned, I also thought you sat on the stbd side to counter act the rotation of the prop.

[Max...]

Which side is an old chestnut on here but I’ve always been SB (as is the RNLI way) but mainly as a biker, twisting a throttle the ‘wrong’ way, albeit with the left hand is odd.

Which side do you sit on?