General Info: Lagoon Catamarans

[Rumbottle]

Lagoon Catamarans of various sizes that I have inspected as a surveyor have some problems.
1) The engine in the aft compartment has piping & wiring passing through the for'd bulkhead into the accommodation. The wiring and pipe holes in the bulkheads were mostly at the bottom of the bulkhead. Water flooded the engine compartment when the tide rose and one hull sank completely, flooding the entire hull. (The crew had anchored the yacht and gone ashore whilst waiting for the tide to rise). It is essential to ensure that all bulkhead penetrations are properly sealed.
2) Various bulkheads are joined to the hull with a compound. There is no GRP cloth overlays over the join. The compound extends about 20mm on each side of the bulkhead. I inspected one larger Lagoon that had completed an ocean passage and noted that the the compound had cracked on both sides of the bulkhead. It would be prudent to glass over the bulkhead to hull joins if an ocean passage is contemplated.

[tuskie]

Originally Posted by Rumbottle

Lagoon Catamarans of various sizes that I have inspected as a surveyor have some problems.
1) The engine in the aft compartment has piping & wiring passing through the for'd bulkhead into the accommodation. The wiring and pipe holes in the bulkheads were mostly at the bottom of the bulkhead. Water flooded the engine compartment when the tide rose and one hull sank completely, flooding the entire hull. (The crew had anchored the yacht and gone ashore whilst waiting for the tide to rise). It is essential to ensure that all bulkhead penetrations are properly sealed.
2) Various bulkheads are joined to the hull with a compound. There is no GRP cloth overlays over the join. The compound extends about 20mm on each side of the bulkhead. I inspected one larger Lagoon that had completed an ocean passage and noted that the the compound had cracked on both sides of the bulkhead. It would be prudent to glass over the bulkhead to hull joins if an ocean passage is contemplated.

Unusual observations for a professional "surveyor".

Firstly, the bulkhead that separates the engine rooms fom the accommodation is usually referred to as an "aft bulkhead". The "for'd bulkhead" is, well, much further forward.
Did you notice that these bulkheads are heavily glassed into the hull? That's because they are both structural. As Lagoon cats are available in a variety of internal layouts, much internal fittout is simply partitions; non-structural and often Sikaflexed or glued into position, allowing them to move with hull flex. If you know more about catamaran design than VPLP, the Lagoon designers, you may wish to improve the hull structure, but I'm all for relying on them to do the job.

Secondly, flooding a hull via the engine room? You stated, that "Water flooded the engine compartment when the tide rose and one hull sank completely, flooding the entire hull".
Funny enough, this normally doesn't happen to Lagoons. Or most other brands for that matter. You neglected to mention how water entered the engine compartment. The only cases that I'm aware of involved the saildrives being ripped out.

You stated; "It is essential to ensure that all bulkhead penetrations are properly sealed."
This demonstrates a lack of professional knowledge. The aft bulkhead of a Lagoon should NOT be watertight. Most Lagoon models are even fitted with a hose with shut off valve penetrating this bulkhead. This allows water that may flood the engine room to enter the bilge at a controlled rate, enabling bilge alarms and activating the bilge pumps to pump it out. If the engine compartment floods at a higher rate than bilge pump capacity it will fill to waterline, but the whole hull should not. Providing bilge pumps and sensor switches are operational.

A professional surveyor would be aware of the environmental laws in many countries prohibiting ordinary bilge pumps in engine compartments. If you are in a country where this doesn't apply, extra pumps in the engine compartments may be a worthwhile upgrade. Others may wish to comment about this modification.

I hope that this clears up some misconceptions.

[arsenelupiga]

i found problematic dealing with people that understand monohulls and try to be experts in cats. Mostly they get it wrong.

However, there is a hole in my L 400 in starboard hull where tubes that engine uses to heat water heater is not sealed. I had to seal it and about to perform full water test now. Need to be prepared if saildrive ripped out.