Spring Launch Checklists for through hulls

Nov 6, 2025
2
Beneteau 331 St Catharines
Just picked up a 2003 331 at the very end of the season. The owner had winterized the water system and head... Didnt touch any through hulls when the boat came out.. Does anyone know of a good checklist or guide for spring when I get her back in the water. I saw in the owners manual a crazy three way valve for the head.. Just want to make sure I dont miss anything. thank you in advance
 
May 17, 2004
5,836
Beneteau Oceanis 37 Havre de Grace
Open and close them a few times each now to make sure they move properly. If there’s anything weird going on with them it’d be better to know about it now than when you want to launch in the spring. Maybe spray some WD-40 in them to clear and avoid corrosion. Assuming they all move fine and look good (no excessive corrosion; no “pink-ing” of the metal) I would just leave them open for the winter. In the spring I close mine just before launch.

The three way valve could be a splitter to send the head discharge into a holding tank or directly overboard. I see you’re from Ontario so I presume you can just leave that on the holding tank setting permanently.
 
Jun 21, 2004
3,036
Beneteau 343 Slidell, LA
I would question the original owner about any thru hull assembly replacement over the past 22 years. It is commonly known that Beneteau built boats of that vintage with fittings that were not a high grade alloy. My understanding is that Beneteau warranted the fittings for 5 years. On my 2006, I have replaced all thru hull fittings, valves, & tailpieces with Groco bronze fittings with BSPP threads. Also, inspect the shaft seal cooling water nipple; they are prone to internal corrosion and breaking off resulting in onboard flooding. If the Volvo shaft seal hasn’t been replaced, now would be a good opportunity. It should be inspected & lubricated annually; replaced at 5 to 10 years. I presume that the 3 way valve that you are referring to is the “Y”valve under the lavoratory cabinet. It is used to divert waste directly overboard or into the holding tank. As @Davidasailor26 mentioned, because of your location, the valve should be physically “locked” into the holding tank position. If you are boarded by local or national law enforcement officials, you could receive hefty fines for non-compliance. Good luck with your new boat. I spent 40 - 50 nonconsecutive charter days on the 331; nice boat! And, welcome to the forum. Lots of good info here and in the archives.
 
Nov 6, 2025
2
Beneteau 331 St Catharines
I would question the original owner about any thru hull assembly replacement over the past 22 years. It is commonly known that Beneteau built boats of that vintage with fittings that were not a high grade alloy. My understanding is that Beneteau warranted the fittings for 5 years. On my 2006, I have replaced all thru hull fittings, valves, & tailpieces with Groco bronze fittings with BSPP threads. Also, inspect the shaft seal cooling water nipple; they are prone to internal corrosion and breaking off resulting in onboard flooding. If the Volvo shaft seal hasn’t been replaced, now would be a good opportunity. It should be inspected & lubricated annually; replaced at 5 to 10 years. I presume that the 3 way valve that you are referring to is the “Y”valve under the lavoratory cabinet. It is used to divert waste directly overboard or into the holding tank. As @Davidasailor26 mentioned, because of your location, the valve should be physically “locked” into the holding tank position. If you are boarded by local or national law enforcement officials, you could receive hefty fines for non-compliance. Good luck with your new boat. I spent 40 - 50 nonconsecutive charter days on the 331; nice boat! And, welcome to the forum. Lots of good info here and in the archives.
THANK YOU! some really good info.. thank you for my welcome.. I am glad I joined!
 

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
23,671
CAL 35 Cruiser #21 moored EVERETT WA
Welcome to the forums.

It must be difficult to have to put your new family member in mothballs for 4 months.

On the other hand there is plenty of time to explore YouTube, books, and the forums here to recharge your mental database on sailing, boat management, and the like.

There are several threads about spring commissioning of plumbing and the like. There may still be time for you the review what was done to the boat to prepare her for winter conditions.

Looks like this week will be a chilly teaser of what is to come this winter.
Congrats on your new to you boat. At 20 years old, planning to replace the thru hulls. Might be a positive thing to explore for spring.
 
Dec 14, 2003
1,445
Hunter 34 Lake of Two Mountains, QC, Can
All good suggestions here except IMHO maybe the use of WD-40 in the thru hulls! I much prefer to use a vegetable oil as WD-40 is mineral-based and is not derived from vegetable sources. Its main ingredients are refined mineral spirits and petroleum base oil, along with other hydrocarbon solvents and inert ingredients. Your new-to-you boat, your choice. And welcome to the forum.
 
  • Like
Likes: jssailem
Jun 21, 2004
3,036
Beneteau 343 Slidell, LA
All good suggestions here except IMHO maybe the use of WD-40 in the thru hulls! I much prefer to use a vegetable oil as WD-40 is mineral-based and is not derived from vegetable sources.
What specific product (s) would you recommend?
 

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
23,671
CAL 35 Cruiser #21 moored EVERETT WA
I like the Corrosion Block and the Boeshield T-9 products.
 
  • Like
Likes: BigEasy
Dec 14, 2003
1,445
Hunter 34 Lake of Two Mountains, QC, Can
What specific product (s) would you recommend?
Since I generally have olive oil in the galley that is what gets used ! Just a smidge while the boat is on the hard then I open and close the thru-hull a few times. They have always worked good since I started doing that 25 years ago. And over the years it's been a combination of salt and fresh water depending on the trips I took. On a more humorous note I wonder if it's because it's ''extra virgin'' oil ? LOL
 
  • Like
Likes: BigEasy