Groaning over 7 knots

[AlphaJustin]

When I run my 72 f25 with direct drive 318 at slow cruise around 6 knots it's perfect no issues but if I crank her up and get her going I get groaning and oscillating drone it was dry docked for 8 years and on land there was no play anywhere and the shaft spun free in neutral and all fluids are perfectly full and clean the boat was repowered and has 170 hours. I'm alright with slow cruising it'll save gas but it's strange and I had to ask. Thanks guys also my phone died so I couldn't get a picture but I'll update my other thread with a picture of the fuel filter soon.

[prowlersfish]

Could be alignment or a motor mount transmitting vibration .

[AlphaJustin]

I can check the motor mounts for play and bolt tightness that should be simple enough. As for alignment is there a way to check that or is it just a tweak and try tweak and try thing until it's right?

[RWS]

STRONGLY SUGGEST you do a shaft alignment.

remove the coupler bolts and insert feeler gauge - bet there is a video on youtube.

Possibly she was blocked improperly and changed the hull?

8 years is a LONG TIME

HOW LONG has she been in the water now?

RWS

[prowlersfish]

I can check the motor mounts for play and bolt tightness that should be simple enough. As for alignment is there a way to check that or is it just a tweak and try tweak and try thing until it's right?

Look at the mounts for collapsing , alignment is done as RWS posted

[AlphaJustin]

s-l400 (2).jpg (35.12 KiB) Viewed 8618 times

Well i put her back in the water around noon yesterday floated her for 3 hours then started moving up the river after about 10 minutes under way when things were nice and warmed up that's when I gave throttle and found this out and since I'm a chicken I only tried it once and for less than 10 seconds backed off and no more noise at all so just went 1 hour up the river to the marina at about 6 knots. I'll look for collapsing mounts and find a tutorial on shaft alignment and report back later today I will keep checking this thread though in case there are other ideas. The picture is how she sat for all those years until I got her.

[The Dog House]

The hull shape changes when the boat is out of the water. It takes 1 - 2 weeks of being in the water for the hull to come back to it's "natural" shape. I would recommend leaving the boat in the water for 2 weeks and then determining the shaft alignment. It may come back into alignment as the hull reverts to it's water shape.

[AlphaJustin]

Giving time to settle before changing things is something I can definitely handle and makes sense. I was wondering if maybe she just hadn't been in the water long enough to reset. I had a small 18 foot that would change every winter and took a day or 2 for the windshield to work again every spring but it never affected the drive line but years verse months is a big difference.

[AlphaJustin]

Prowler all four mounts look in the same shape as the one in this picture basically look new. Also since I'm posting this picture anyone have valves like these and if so how do you know which way is open? Haha I just hijacked my own thread.

[Diverted Income]

Groco SV Series valve. That one is almost completely open. Best bet is to pull the rubber "plug" out when the boat is out of the water and grease it with a non petroleum based grease. Good valves but parts are non existent. Pretty easy to do.

[AlphaJustin]

Thank you diverted it's got a lock screw on the backside that I like you can set it open or closed and know it won't change i just couldn't tell which position it was in I just knew I had water flowing out the exhaust so it must have been at least semi open.

[The Dog House]

Giving time to settle before changing things is something I can definitely handle and makes sense. I was wondering if maybe she just hadn't been in the water long enough to reset. I had a small 18 foot that would change every winter and took a day or 2 for the windshield to work again every spring but it never affected the drive line but years verse months is a big difference.

Most likely the 18 footer was a sterndrive. Hull shape doesn't really affect the alignment of sterndrives like it does an inboard. Hull shape is much more important with an inboard.