How does loading effect draft?

[Gunn]

So we've been looking for a new boat for what seems like forever. And at the same time, we've been working towards getting the permits to build our own pier at our home that we've lived in for the last five years. After 18 months, I now have the state permit in my hand!

Only issue was that we were limited by how long the pier could be, and we're tucked away in the corner of this big river. So at the end of our pier, 175 feet outward, the water is about 4-1/2 feet at normal high tide, about 3-1/2 at low tide; I've had a stick out there with tick marks on it for over a year to constantly track it.

When looking at boats we'd like to upgrade to (ie: 260DA), I'm always concerned with the draft. For the 270DA, pre-1998, the draft is listed as 36" - stern drive down, 23" - stern drive up. In 1999, the draft was now listed as 43" - stern drive down, 23" up. I noticed they added a 1,000lbs to the weight.

But I assume these measurements are best case, dry-weight numbers. What I'd like to know is what happens when I fill it up with fuel, water, gear, etc. Then what happens when I add 8 people?? Has anyone ever noticed the difference in their draft when loaded, or measured the difference than what is listed?

I know we'll be cutting it close, especially at low tide. And I'd hate to be restricted to when we can leave and when we need to be back home by!

Oh, and we'll also have a lift that will take up 8" off the bottom... :smt009

Thanks,

Tom

 

[Zorba]

The draft number may also differ because of the Out Drive. The 270 May have had Alphas in 2000 but the 260 could have had a Bravo Drive. That may be the difference your seeing in Stern Drive Down Numbers.

 

[Four Suns]

With a boat bottom 1 foot off the river bottom, you are going to be kicking up and sucking up mud like there is no tomorrow. worrying about an inch or two isn't going to matter. That's the bad news.

The good news is this (form someone who was on the river). Mark your approach and exit with some PVC pipe and make sure you use the same "channel" coming into your dock. The props will end up digging a channel for you over time... I had 8 feet of water on my dock and I backed the boat in and then revved it up and blew out 2 feet of the bottom and it went up on the beach. So when you get bored some Saturday, go dig yourself a channel. Make sure you keep the crap you are digging up behind the boat and not under it.

If you hurt your boat, I'm not responsible.

 

[Kendall]

Hi Tom:

I was in pretty much the same situation you are in a month ago and I have worked hard to get my 3.5' of water to work with our 2006 260 DA w/B3. I'm not sure that the draft numbers given by Sea Ray change much with full load but I haven't noticed much difference in how ours sits in the water when full or light.

I had to dig out our slip at the front of the boat as the 260's keel stays pretty deep almost to the front of the boat unlike a typical bowrider...so this was my main problem. Since I would have had to use 6" cradle beams along with 2X12's for support I would have needed approximately 18" just for my boat lift to clear. For this reason I chose to go with straps which I'm happy with so far.

I have attached some photos (try to resize them) so you can see what I was up against.

I don't believe you will have a problem between 3.5' and 4.5' of water....I sure will if they drop the lake much past typical levels....

Let me know if I can answer any questions as I know I spent a lot of time worring about this issue.

Good luck,

Kendall

 

[Gunn]

Great info, as always. Good idea too Gary, that may just get me the clearance to feel comfortable with taking the boat in and out, anytime. Scott's idea is good too, as even though my lift will be beside the pier, at the end, I could dock at the end of pier, across it, and offload. That'd get me a boat-length away from the shore anyway.

I wondered about the lifts with straps. Then I wouldn't have an 8" beam under the boat to clear (which is the size of the lift I've decided to purchase). Who is the manufacturer of that lift? Do they have a website I could take a look at?

The pain about all of this is that if I could have extended the dock a lousy 25 more feet, I'd have another 18" of water; it really begins to drop off there. But the neighbor wouldn't budge on the deed restriction any further than 175' (still better than the orginal 125')...

Tom

 

[Kendall]

Great info, as always. Good idea too Gary, that may just get me the clearance to feel comfortable with taking the boat in and out, anytime. Scott's idea is good too, as even though my lift will be beside the pier, at the end, I could dock at the end of pier, across it, and offload. That'd get me a boat-length away from the shore anyway.

I wondered about the lifts with straps. Then I wouldn't have an 8" beam under the boat to clear (which is the size of the lift I've decided to purchase). Who is the manufacturer of that lift? Do they have a website I could take a look at?

The pain about all of this is that if I could have extended the dock a lousy 25 more feet, I'd have another 18" of water; it really begins to drop off there. But the neighbor wouldn't budge on the deed restriction any further than 175' (still better than the orginal 125')...

Tom

Tom:

You can get the straps at www.lunmarboatlifts.com

My lift is made by Doozie who you can contact at www.itsadoozie.com

Kendall

 

[mwph]

Is your neighbor being a Jacka$$ or does he have a point? If its the former ... A 1/2 dozen loads of dirt would make a nice little pininsula(sp). Say 8' wide, 20' long. Cover it up w/grass, plants & shrubs. Delivered during the initial stages of pier construction, it would seem normal.:grin:

 

[sbw1]

Wakes, if you have them, can affect things. We have some friends who slip their boats in shallow areas and they can hit bottom coming into their slips when a jerk goes by as they are pulling into or out of their slips. Hopefully you are in a no wake zone.

 

[unlvrebel]

..., 175 feet outward, the water is about 4-1/2 feet at normal high tide, about 3-1/2 at low tide; ...

I'm a little ignorant... I didn't know that rivers had tides???:huh:

Anyway, get a backhoe. Or absent that, a shovel.

Seriously, good luck.

 

[jitts3]

With a boat bottom 1 foot off the river bottom, you are going to be kicking up and sucking up mud like there is no tomorrow. worrying about an inch or two isn't going to matter. That's the bad news.

The good news is this (form someone who was on the river). Mark your approach and exit with some PVC pipe and make sure you use the same "channel" coming into your dock. The props will end up digging a channel for you over time... I had 8 feet of water on my dock and I backed the boat in and then revved it up and blew out 2 feet of the bottom and it went up on the beach. So when you get bored some Saturday, go dig yourself a channel. Make sure you keep the crap you are digging up behind the boat and not under it.

If you hurt your boat, I'm not responsible.

I was thinking the same but with an excavator, but have no idea how to get one out that far. Gary may just have it.

Is your neighbor being a Jacka$$ or does he have a point? If its the former ... A 1/2 dozen loads of dirt would make a nice little pininsula(sp). Say 8' wide, 20' long. Cover it up w/grass, plants & shrubs. Delivered during the initial stages of pier construction, it would seem normal.:grin:

Now this is more like me.:thumbsup:

 

[Gunn]

I live on a river that opens into the Potomac River, near the Chesapeake. It is brackish, tidal waters. All connected to the Atlantic, so yes we have tides!

It's a pretty large river here, and our pier will be wide open along the shoreline, so yes, there are waves. Usually pretty gentle, only getting above 1' in pretty bad weather.

Thanks for the info on the straps, I'll check it out.

 

[Hampton]

If you add 500 pounds of gear, you have to displace an additional 500 pounds of water to keep the boat afloat. There are 231 cubic inches in a gallon of water, which weighs about 8.35 pounds, depending on temp and other things. So, there is .036 pounds of water in a cubic inch and 27.8 cubic inches in a pound of water. If you add the 500#, you displace 13888 cubic inches of water.

If you boat has 6' (72") of beam in the water, and maybe about 12 of length in the water at rest (84"), then it has 6048 square inches in the water at rest. That means adding 500# of water lowers your boat about 2.3" if it squats evenly.

Kind of an around about way of getting there, but for every 217 pounds you add, your boat will sit 1" lower in the water. If your beam is wider, or the length in the water is more or less, you'll have to adjust this amount.

You can add weight to make your boat sit higher too. If you add weight to the bow to more evenly distribute the weight, you can increase the square inches in the water and raise not only the stern, but the entire boat. EDIT - OK, not the entire boat, but you can raise the lowest point by putting more boat in the water, even by adding weight.

 

[tmhudson2]

... at the end of our pier, 175 feet outward, the water is about 4-1/2 feet at normal high tide, about 3-1/2 at low tide; I've had a stick out there with tick marks on it for over a year to constantly track it.

I know we'll be cutting it close, especially at low tide.

How much lower is the low tide during a full moon? Will this effect your situation?