Boat lower in water

[gbmacca]

'Morning all,

Here's a question for you.

My boat is a wooden 55' Chris Craft Constellation, which has not been slipped for a few years - so would have growth on bottom.

It is our wet season and the river in which I am moored is salt, but at this time of the year, with fresh water pouring down from the hills, I would expect the upper level of the water, to be relatively fresh.

The boat always takes on water - but minimal - with pump going off every 12 hours or so, usually tripped by a wake - for less than 30 seconds - with no increases noted.

So no extra water entering and most of internal hull remaining dry.

However, my boat is sitting 1 - 2 inches lower in the water!

Is it the weed - which I can't see as water is currently coffee coloured, is it the fresh water, or is the timber (ply) absorbing water and heavier?

I can't sleep at night ---

Cheers

Gbmacca

[nwdiver]

You'll drop a bit in fresh water, ask the overloaded fishing boats that have sunk going from the sea into a river

[gbmacca]

Yeah - have heard of them struggling when overloaded.

Was wondering - as boat came from Seattle - virtually fresh water - and sat higher back then - if there was a more ominous problem.


Cheers

[JPA Cate]

It could be the fresh water, I certainly float higher in salt water. But really, won't you feel better if you haul her out, get rid of the bouillabaisse and have a good look-see at the hull? Weigh the bouillabaisse after scraping, before it dries out, it may surprise you. I bet you've seen untended moorings mostly submerged from the biofouling....it weighs down the pennant and the ball.

Ann

[coopec43]

"A floating vessel displaces its own weight in water. Sea water is denser than fresh water. Your vessel will have to displace a greater volume of fresh water than seawater to float. Your vessel will float with less freeboard, that is lower in the water, when you move it to the river".
https://www.quora.com/When-a-ship-is-moving-on-seawater-and-it-enters-a-river-and-moves-inland-is-it-expected-to-rise-sink-or-maintain-the-same-level-of-draft?page_size=20#!n=12

[Lepke]

Worms are a worry in salt water. If your bottom paint has lost its juice, worms will get in the wood and bore 3/8" holes.
Pic is a keel piece I saved of my first big boat, 1940 65' Chris-Craft. About 1961. Surveyor was checking the keel with an ice pick, hit a worm hole, and the pick went in to the hilt. I bought the boat at auction. It had sat a few years in San Francisco Bay near the bridge.
Also keep rock salt or borate in the bilge. Salt preserves wood.

[Don C L]

Originally Posted by JPA Cate

It could be the fresh water, I certainly float higher in salt water. But really, won't you feel better if you haul her out, get rid of the bouillabaisse and have a good look-see at the hull? Weigh the bouillabaisse after scraping, before it dries out, it may surprise you. I bet you've seen untended moorings mostly submerged from the biofouling....it weighs down the pennant and the ball.

Ann

I dunno but maybe that bouillabaisse is what's holding her up!

[valhalla360]

Weeds shouldn't have much effect as they are close to the same density of water, so they while they will add weight, they will also displace more water (outside the hull shape).

Shellfish on the other hand...their shells are significantly more dense than water, so even though they displace extra water, they weigh more than the extra displacement.

[jhulmer]

yup! Archimedes spent a lot of time on this principle.


wikipedia:



Archimedes' principle states that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces and acts in the upward direction at the center of mass of the displaced fluid.[1] Archimedes' principle is a law of physics fundamental to fluid mechanics. It was formulated by Archimedes of Syracuse.[2]



Salt water weighs more because of the dissolved salts so it produces more buoyancy than freshwater.



Jim

[Cadence]

Originally Posted by gbmacca

'Morning all,

Here's a question for you.

My boat is a wooden 55' Chris Craft Constellation, which has not been slipped for a few years - so would have growth on bottom.

It is our wet season and the river in which I am moored is salt, but at this time of the year, with fresh water pouring down from the hills, I would expect the upper level of the water, to be relatively fresh.

The boat always takes on water - but minimal - with pump going off every 12 hours or so, usually tripped by a wake - for less than 30 seconds - with no increases noted.

So no extra water entering and most of internal hull remaining dry.

However, my boat is sitting 1 - 2 inches lower in the water!

Is it the weed - which I can't see as water is currently coffee coloured, is it the fresh water, or is the timber (ply) absorbing water and heavier?

I can't sleep at night ---

Cheers

Gbmacca

If you are not taking on any water to speak of and the salinity has decreased lose your sleep mover the job removing the braincells. Not the shell the base.

[taxwizz]

Maybe you are just sinking....??

[psk125]

You haven't heard about sea-levels rising?
The few inches you mention seem to correlate with this:
https://oceanservice.noaa.gov/facts/sealevel.html

[georgeg305]

You haven't heard about sea-levels rising?
The few inches you mention seem to correlate with this:
https://oceanservice.noaa.gov/facts/sealevel.html


You are joking! Right?

[taxwizz]

Originally Posted by georgeg305

You haven't heard about sea-levels rising?
The few inches you mention seem to correlate with this:
https://oceanservice.noaa.gov/facts/sealevel.html


You are joking! Right?

Nope.
Sea levels are rising.
Sell your ocean front property....Quickly.
(Unless you are a believer in Fake News.)

[psk125]

Originally Posted by taxwizz

Nope.
Sea levels are rising.
Sell your ocean front property....Quickly.
(Unless you are a believer in Fake News.)

If you're in Toronto you can probably wait a year or two before it gets up that far.