Assessing Hull Trim at Transom Using Engine Splash Well Drains and Waterline

[dsullivan]

Q1: on a 1988 OUTRAGE 22 (assumed to have a notched transom), where will the drains in a sink-style engine splash well be located relative to the waterline at the transom if the hull is not sitting “too low” at the stern?

Q2: what should be the distance from the top of the notched portion of the transom to the waterline?


BACKSTORY
I own a 1989 OUTRAGE 18 with a full-width engine splash well. I am assessing a 1988 OUTRAGE 22 (assumed to be a notched transom) and I want to determine if the boat is sitting too low at the stern.

NOTE: my belief is that the drains on a 1988 OUTRAGE 22 (notched transom) SHOULD sit lower down under the water [than the drains on my 1989 OUTRAGE 18.

[jimh]

Q1: on a 1988 OUTRAGE 22 (assumed to have a notched transom), where will the drains in a sink-style engine splash well be located relative to the waterline at the transom if the hull is not sitting “too low” at the stern?

An older (pre-c.1990) OUTRAGE 22 notched transom hull has only one drain in the engine splash well. The drain is located deep in the splash well and is always kept open to the sea, although a ball-valve scupper may be in place to reduce entry of water when backing down.

Cf.: https://continuouswave.com/whaler/refer ... elfBailing

The trim on the boat cannot be assessed by using the deep drain (in the sink-style engine splash well) position relative to the waterline as the deep drain will always be submerged.

Q2: what should be the distance from the top of the notched portion of the transom to the waterline?

The freeboard is surprisingly limited. See Figure 1 for a good photograph of an OUTRAGE 22 notched transom boat showing the freeboard at the transom:


Fig. 1. An older OUTRAGE 22 notched transom boat with a single relatively light two-stroke-power-cycle engine in static trim with one crew in the aft cockpit

[dsullivan]

Thanks for the info. Just have some follow up questions.

The freeboard is surprisingly limited. See Figure 1 for a good photograph of an OUTRAGE 22 notched transom boat showing the freeboard at the transom:

Q3: in the image provided in Figure 1, is the freeboard of the transom considered to be sitting lower than normal or is that how it should look?

Q4: do you know approximately, the transom freeboard height in that image by chance?

The trim on the boat cannot be assessed by using the deep drain (in the sink-style engine splash well) position relative to the waterline as the deep drain will always be submerged.

Q5: If the deep drain is left open and will be submerged, would that mean that the waterline that fills into the sink-style splash well would be at the same level as the waterline outside the boat?

Q6: Is it possible to assess if the static trim is too low by how far up into the sink-style splash well that the water fills up to?

Q7: What options are there to determine if the static trim of a 1988 notched transom outrage 22 center console is sitting too low in the water, either from water logged foam, or a heavier outboard engine, etc?

Additional background: the boat I am looking at has a 2005 E-TEC 225, but the questions are more in general in case I look at other similar boats with different engines.

[jimh]

Q3:In the image provided in Figure 1, is the freeboard of the transom considered to be sitting lower than normal or is that how it should look?

The boat show in Figure 1 is a very normal hull with a very normal engine with a not-very-heavy guy standing near the stern in cold freshwater. On that basis I would assume that the amount of freeboard at the notched transom is very normal.

Q4:Do you know approximately, the transom freeboard height in that image by chance?

I do not know the exact measurement, but you are welcome to infer some measurement by careful analysis of the image. For example you could measure the distance between the stern towing eyes and then use that as a scale to measure the freeboard.

Q5: If the deep drain is left open and will be submerged, would that mean that the waterline that fills into the sink-style splash well would be at the same level as the waterline outside the boat?

Yes, that is how water works.

Q6: Is it possible to assess if the static trim is too low by how far up into the sink-style splash well that the water fills up to?

The water line in the deep engine splash well is going to be the same as the waterline on the transom, which is much easier to see or measure.

Q7: What options are there to determine if the static trim of a 1988 notched transom OUTRAVE 22 is sitting too low in the water, either from water logged foam, from a heavier outboard engine, or from something else?

The amount of freeboard at the transom notch is the best indicator of excessive engine weight or other causes of the hull static trim being down by the stern.

The big open transom of a notched transom OUTRAGE 22 might look strange, but there are two good reasons for it:

• the wide notched transom is designed to accommodate twin engines
• a low transom height will allow the cockpit to very rapidly shed water if the boat is swamped by a big wave.

In actual operation of the boat, having water come over the transom would likely only ever occur if you were making sternway into waves.

ANOTHER METHOD TO ASSESS TRIM
There should be a cockpit sump on the starboard side of the cockpit near the transom which will collect any water running off the cockpit deck. This sump has a drain to the sea through the hull bottom. With the boat at rest, remove the drain plug from this sump. Water will begin to flow into the sump. The level of water that rises in the sump may slightly overflow the sump and put water on the deck, but the level should not rise very much--if any--above the sump. If the water in the sump with an open drain to the sea begins to flood the stern cockpit with several inches of water, then the boat trim is too far down by the stern.

ANECDOTE
When I was selling my REVENGE 20 W-T boat, I took the prospective buyer and his wife on a sea trial in Lake Erie. When we were about a mile or so offshore, I went to the cockpit sump on starboard in the stern, and I removed the sump drain. The water level in the sump rose a few inches but was completely contain in the sump area. The buyer's wife was quite impressed with demonstration. They bought the boat.