Shallow water and drive trim

[windchaserb]

Question about drives and somewhat shallow water.

I've always owned sailboats but this Formula 280 SS is my first powerboat. I'm boating on the south shore of Cape Cod and finding that the water, at low tide, where I keep my boat a bit shallow to say the least. I've managed to hit bottom with the propeller heading out to open water a few times. It was suggested I raise the drives to (hopefully) avoid that so I began reading the manual. It mentions using power trim or even the trailer switch to raise the drives (although it says not to run at greater than 1200 rpm with the trailer switch).

Which is recommended for shallow water ? power trim or trailer switch?

I?d estimate that I may need 4 -6 inches of extra water to avoid bottoming the propeller.

 

[southkogs]

No wake speeds with the sterndrive, you can use your trailering tilt, and you can probably get it up rather high. In many cases that's referred to as "shallow water" drive. Once you start getting close to that 1200 range you need to stay within trim range or you'll damage your system.

 

[southkogs]

Meant to put a "welcome aboard" in there too, but I had an argument with the POST REPLY button

 

[Fastatv]

It really depends on how high you need to raise the drives to keep the props and water pump pick ups out of the crud. For me, the best thing to do is try to stay out of very shallow water....or wait for the tides to come in ( when I resided in FL ). Trimming up the drives will not usually get a great deal of up traval distance, and in some cases, it may be required to bring the drives up a bit more using the trailer function. I had to do that yesterday on a fresh water lake. Anyway, I never bring mine up as to where the prop is out of the water....always in the water. And its great you read the manual...wonderful. When in trailering "trim", I never go above the standard idle, however, standard idle will generally keep you moving forward unless there is a wind. When in the trailering range, the drive U-joints are not very happy so use caution when doing this.....and keep the RPMs very low. Good luck!

 

[agallant80]

I would not go in to the trailer position if I could avoid it, You should go slow too, less chance of kicking up sand which will eat your impeller.

 

[tpenfield]

Question about drives and somewhat shallow water.

I've always owned sailboats but this Formula 280 SS is my first powerboat. I'm boating on the south shore of Cape Cod and finding that the water, at low tide, where I keep my boat a bit shallow to say the least. I've managed to hit bottom with the propeller heading out to open water a few times. It was suggested I raise the drives to (hopefully) avoid that so I began reading the manual. It mentions using power trim or even the trailer switch to raise the drives (although it says not to run at greater than 1200 rpm with the trailer switch).

Which is recommended for shallow water ? power trim or trailer switch?

I?d estimate that I may need 4 -6 inches of extra water to avoid bottoming the propeller.

I boat on Cape Cod and also have fairly shallow water inside the harbors, etc. I have a Formula 330SS, similar setup to the 280SS. so, I assume that you have the Bravo 3 outdrives (twins) right?

Full draft on those boats is around 3 feet, maybe a bit more. The hull itself draws about 2 feet, maybe 27 inches. During low tide, my mooring is in about 30 inches of water, so I have to raise the outdrives up beyond their trim limits. Of course you can only proceed at an idle with the drives up in that position. Worst cases, I have some of the crew go sit up on the bow to raise the stern a bit. I had to do this over at Edgartown once when I got trapped in a bit by a sand bar & low tide.

So, using the trim switch does not bring the outdrive up very much. You need to use the trailer switch to get the outdrive up further, but not too far.

You are generally fine to go at idle speed (800 RPM) with the drives tilted up a bit beyond their trim limit. I do not run them tilted all the way or even nearly all the way up. You just want to make sure that the drive is tilted up enough so that if you bottom out or hit some thing hard, the leading edge of the outdrive will be touching and not the propellers. With the outdrive tilted up and the engines at idle, your speed will only be a few mph, so less likely to hurt something if you bottom out.

Obviously, know where the chanels are and where the rocks are too. If your harbor is anything like mine, not everything is marked . . . so you just gotta know.

 

[windchaserb]

Thanks for the info. Yes on the Bravo 3's - twins.

I'm ok at the mooring - just along one of the channels out to open water is bad. I'm going out in my dingy with a stick to try to find the optimal depth but still expect to have to trim.

Good point about tilting so its not the propeller hitting.

Thanks everyone.

 

[JimS123]

With the boat on the trailer, raise the drives until the prop is just above the keel. Note that point on your trim gauge so you can go there in the future. In my case, if all the way down is "1" and all the way up is "5", I raise mine to the #4 position.

The trim button will not work because you will have to go above the trim range to clear the bottom. My manual says nte 1200 rpm. I have run her at 1000 for 31 years with no problems. Our regular "Sunday Cove" requires me to cross a 50 yard 2' deep sand bar.

 

[tpenfield]

Thanks for the info. Yes on the Bravo 3's - twins. I'm ok at the mooring - just along one of the channels out to open water is bad. I'm going out in my dingy with a stick to try to find the optimal depth but still expect to have to trim. Good point about tilting so its not the propeller hitting. Thanks everyone.

Windchaser, I sent you a Private Message ( at least I think I did ) so it should be in your message center inbox.