Thru hull intake

S

Sea Señor

Member
Aug 31, 2021
55
South shore, Long Island NY
Boat Info
2010 280 Sundancer
Engines
Mercruiser 350 MAG MPI w/bravo 3 drive
Hi all, it was recommended by my mechanic to install a thru hull intake on my 280 sundancer. It will allow more water into the engine for cooling and will help prevent overheating issues. I have a mercruiser 350 mag mpi with catalytic converters so I have a lot of annoying sensors that are sensitive to overheating. It seems to be a common modification. Is it expensive and worth it? Thanks for your input
 
89P270 posted this. i copied for this, he wont mind

"The fix for this as noted above is add Thru Hull seacock cooling. When you do this, you have to maintain the drive OEM water flow too or you will overheat the outdrive."
 
As someone who did the mod to a twin engine boat, yes its worth it - the parts are pricey, but you only need one set - you should have a pad glassed in for the placement of the seacock (ac, gennie, etc) I would go the route of getting the block off plate for the outdrive and cutting a section out of the exterior hose so the drive gets flow through cooling.....the alternative is to install a "Y" and draw water from both sources......I really don't like that for two reasons: Still no way to shut water off coming in the boat in the event of a hose failure (reason enough alone to do the mod) and; if the tube in the outdrive collapses collapses you will never Know and the drive will not get the flow through cooling it needs
 
I would also add an intake strainer basket and a ball valve shut off where the thru hull enters the boat.
 
Block off kit if you abandon the water pickup from the drive:

upload_2021-9-1_15-39-31.png
 
Ididntdoit said:
As someone who did the mod to a twin engine boat, yes its worth it - the parts are pricey, but you only need one set - you should have a pad glassed in for the placement of the seacock (ac, gennie, etc) I would go the route of getting the block off plate for the outdrive and cutting a section out of the exterior hose so the drive gets flow through cooling.....the alternative is to install a "Y" and draw water from both sources......I really don't like that for two reasons: Still no way to shut water off coming in the boat in the event of a hose failure (reason enough alone to do the mod) and; if the tube in the outdrive collapses collapses you will never Know and the drive will not get the flow through cooling it needs
Click to expand...

@Ididntdoit any pics Mike ??? Hoping to do this in the off-season as well. I've seen advice for a twin engine go both ways: some say one thru hull and strainer is enough to supply both engines, others say you need one setup per side. I'd like to do one setup to feed both engines and block off the drive input. Yes those of us stuck up here have an off season. A LONG off season :mad:
 
I bought a 2010 310 late last season that came off a fresh water lake so being on salt water I decided to add closed cooling. The addition of closed cooling required thru hull water pickups. I see a difference in water pressure and as far as the drives overheating I don't think I've noticed a difference. I will be adding drive showers though as a precaution really because they're cheap insurance. We added a thru hull pickup for each engine but no strainers just South Bay strainers on the bottom of the boat.
 
What site do you guys use for oem parts? Looking to order a new cable release mechanism for the rear seat that folds down to a sun pad. The old one broke
 
I have a single engine 6.2L/B3 and the thru hull makes a huge difference on cooling. Mine is set up as a dual pickup per merc recommendation, and it’s impossible to get the temp over 155 when the thru Hull is open. If I close the seacock it runs closer to 170 when doing water sports.

I did the dual pickup to make it easier to flush the drive. You close the seacock and use the muffs. The fake a lake can get difficult depending on the location of your thru hull
 
Sea Señor said:
What site do you guys use for oem parts? Looking to order a new cable release mechanism for the rear seat that folds down to a sun pad. The old one broke
Click to expand...

It really depends what you're looking for ...

There are several sites like the ones PL posted, plus other go-tos like boats.net, Iboats, Great Lakes Skipper -- plus Amazon and eBay. When all else fails and you can't find it by searching, especially if it's a model-specific rarer part like that seat cable and you can't find it anywhere else, call the parts dept at a Sea Ray dealer and they can check directly with Sea Ray. That was the only way I could get a stovetop safety switch.
 
Phil S said:
@Ididntdoit any pics Mike ??? Hoping to do this in the off-season as well. I've seen advice for a twin engine go both ways: some say one thru hull and strainer is enough to supply both engines, others say you need one setup per side. I'd like to do one setup to feed both engines and block off the drive input. Yes those of us stuck up here have an off season. A LONG off season :mad:
Click to expand...

Hi Phil - I'll look for pics......definitely need 2 seacocks (with scoops) and 2 strainers - on one of the glassed in pads I had the a/c and starboard motor seacocks and the other had the gennie and port motor - the strainers were installed on the "wall" created by the dropoff from the shelf the gennie and batteries sit on
 
Ididntdoit said:
Hi Phil - I'll look for pics......definitely need 2 seacocks (with scoops) and 2 strainers - on one of the glassed in pads I had the a/c and starboard motor seacocks and the other had the gennie and port motor - the strainers were installed on the "wall" created by the dropoff from the shelf the gennie and batteries sit on
Click to expand...

That would be great, thanks! I was hoping I could use the pads that are already there.

So just wondering ....

If you go this route and block of the drive as a water source, what if you need to run the engines when it's out of the water? You can't do the muffs anymore. Maybe attach another ball valve that accepts a garden hose?
 
Phil S said:
That would be great, thanks! I was hoping I could use the pads that are already there.

So just wondering ....

If you go this route and block of the drive as a water source, what if you need to run the engines when it's out of the water? You can't do the muffs anymore. Maybe attach another ball valve that accepts a garden hose?
Click to expand...

That's the beauty of doing this - just shut the seacock, take the cover off the strainer and drop a garden hose in it - I used this method to flush after each use - you can winterize by pouring pink in the strainer with the motor running too (as long as the t-stat is open) - but I prefer to drain the block completely (including removing and "poking out" the block drains) and manually fill with the pink. Obviously this all applies to a RWC system and bravo drives....
 
Something like this Perko for the strainers? It looks very similar to my AC and genny strainers.

61iHbnjBzML._AC_SL1000_.jpg
 
ColoSR said:
Mine is set up as a dual pickup per merc recommendation,
Click to expand...
So I have done it on two different boats, both twin engines. Firtst was my 1989 Pachanga twin 350s/Alphas when I upgraded to new bobtails in 2012. Not sure I have any pics of the actual water pic up in my thread under classifieds "1989/2012 Pachanga". But the second boat I did was a Rinker 342 fiesta Vee with twin 6/2L MX/Bravo three's. Here are some picks of the set up. As noted, for Bravo 3, mercury recommends keeping the outdrive to engine cooling line. This is critical to keeping the hot running Bravo III cool. this water circulates through the outdrive and up to the engine. If your concerned about water intrusion from damaged water line, add an extra in line shut off valve. I didnt as I wasnt concerned about breaking a line in the bilge. the Rinker was a 2002 and I did the upgrade in 2018. So for 16 years prior, the water cooling lines never failed. Good maintenance ensures this. Now for the Bravo drives on the Rinker, the prior owner had added outdrive showers. So, upgrading with thru hull pick ups AND the outdrive showers, AND keeping the OEM cooling from the Bravo to engine Impeller line you have the best of all worlds. Yes, also, you can see I had sea strainers added too. I didnt have the strainers on the pachanga because it was the first upgrade I did and I wasnt aware of it. Some cautions about this upgrade -
1. Absolutely make sure if you have a mechanic do the work (like I did on both boat set ups) work with them to ensure you are happy with where the pick ups are to be placed. See photo of the Rinker set up. the mechanic put the thru hulls in from of the v-belts on both engines. It looks like a lot of room but its not. thats about a 12 inch space and about 3 feet down to it. I had to make a special tool to shut the seacock when winter time to be safe for flooding - If the boat is on the water for long periods, you want the seacocks closed to prevent potential flooding/siphoning. Rare, but can happen. On the pachanga, I think I pissed the mechanic off by keeping my two OEM engines/outdrives so he installed the pick ups behind each engine - near impossible to get too. Ugghh. Then again, I did sell the OEM bobtails on craiglist for about $3,500 total.
2. If trailering, try to have the pick ups installed where they wont be between the hull and a bunk. Again, Pachanga set up wasnt considered and they were between bunk and hull. Not a huge deal but again, a potential for seal breach around the cutout from stress/vibrations.
3. Cost - Well, they are boats. If you have a mechanic/shop do the work which I recommend (warranty), in 2012 I would say that piece of the retrofit on the pachanga ran me what, $2,500 (work done by Lake Union Searay). But there were economies from the engines being already pulled for new set ups and I worked the service manager there for two years to get "The Deal". in 2018, the Rinker job was done when I replaced both Bravo IIIs - Again, economies due to significant other work. This work was done by Seattle Boat _ Probably the most expensive location in Seattle area but they do quality work - Adam, the lead mechanic is excellent there!. This work was for the thru hulls probably more like (STET not 4K see below) due to additional stuff added like the strainers. If I can find the receipt, I'll come back and edit with the exact cost. Edit - So here is the parts cost for the Rinker twins: The labor is shown as $716 but I would say to add double as I did the work in Jan-March where they run a 1/2 off labor special.
THRU-HULL INTAKE STRAINERS
-- Part # --------- Description --
B/A00IS100 THRU-HULL INTAKE STRAINERS 2.00 85.68 171.36
HOS100-1006 TRIDENT 100/250 WIRED WET 8.00 15.30 122.40
3852476 PLUG OFF CAP 1.00 14.75 14.75
ACC32024 1" HOSE TO 3/4" PIPE FITTING 4.00 14.67 58.68
GROARG-1000 SINGLE RAW WATER STRAINER 2.00 297.00 594.00
==============
Labor Total : 716.00
Parts Total : 961.19

The irritating thing about these adds - Sea Ray service manager wouldnt do the Bobtail replacement without the added thru hulls as Mercury had noted for years, alpha impellers were notorious for low volume production for performance boats and the service manager wouldnt warranty without the additional cooling. FOr the Rinker, the manufacturer actually put the thu hull additional cooling in on some 342 Fiesta Vee's but apparently was an option. Stock set up was through the drives. These are all things I watch for now when looking at my next boat. Things you learn from years of boating, right?

Port side Y.jpg Sea Strainers.jpg Starboard Thru Hull.jpg
 
Last edited:
89P270 said:
So I have done it on two different boats, both twin engines. Firtst was my 1989 Pachanga twin 350s/Alphas when I upgraded to new bobtails in 2012. Not sure I have any pics of the actual water pic up in my thread under classifieds "1989/2012 Pachanga". But the second boat I did was a Rinker 342 fiesta Vee with twin 6/2L MX/Bravo three's. Here are some picks of the set up. As noted, for Bravo 3, mercury recommends keeping the outdrive to engine cooling line. This is critical to keeping the hot running Bravo III cool. this water circulates through the outdrive and up to the engine. If your concerned about water intrusion from damaged water line, add an extra in line shut off valve. I didnt as I wasnt concerned about breaking a line in the bilge. the Rinker was a 2002 and I did the upgrade in 2018. So for 16 years prior, the water cooling lines never failed. Good maintenance ensures this. Now for the Bravo drives on the Rinker, the prior owner had added outdrive showers. So, upgrading with thru hull pick ups AND the outdrive showers, AND keeping the OEM cooling from the Bravo to engine Impeller line you have the best of all worlds. Yes, also, you can see I had sea strainers added too. I didnt have the strainers on the pachanga because it was the first upgrade I did and I wasnt aware of it. Some cautions about this upgrade -
1. Absolutely make sure if you have a mechanic do the work (like I did on both boat set ups) work with them to ensure you are happy with where the pick ups are to be placed. See photo of the Rinker set up. the mechanic put the thru hulls in from of the v-belts on both engines. It looks like a lot of room but its not. thats about a 12 inch space and about 3 feet down to it. I had to make a special tool to shut the seacock when winter time to be safe for flooding - If the boat is on the water for long periods, you want the seacocks closed to prevent potential flooding/siphoning. Rare, but can happen. On the pachanga, I think I pissed the mechanic off by keeping my two OEM engines/outdrives so he installed the pick ups behind each engine - near impossible to get too. Ugghh. Then again, I did sell the OEM bobtails on craiglist for about $3,500 total.
2. If trailering, try to have the pick ups installed where they wont be between the hull and a bunk. Again, Pachanga set up wasnt considered and they were between bunk and hull. Not a huge deal but again, a potential for seal breach around the cutout from stress/vibrations.
3. Cost - Well, they are boats. If you have a mechanic/shop do the work which I recommend (warranty), in 2012 I would say that piece of the retrofit on the pachanga ran me what, $2,500 (work done by Lake Union Searay). But there were economies from the engines being already pulled for new set ups and I worked the service manager there for two years to get "The Deal". in 2018, the Rinker job was done when I replaced both Bravo IIIs - Again, economies due to significant other work. This work was done by Seattle Boat _ Probably the most expensive location in Seattle area but they do quality work - Adam, the lead mechanic is excellent there!. This work was for the thru hulls probably more like 4K due to additional stuff added like the strainers. If I can find the receipt, I'll come back and edit with the exact cost.

The irritating thing about these adds - Sea Ray service manager wouldnt do the Bobtail replacement without the added thru hulls as Mercury had noted for years, alpha impellers were notorious for low volume production for performance boats and the service manager wouldnt warranty without the additional cooling. FOr the Rinker, the manufacturer actually put the thu hull additional cooling in on some 342 Fiesta Vee's but apparently was an option. Stock set up was through the drives. These are all things I watch for now when looking at my next boat. Things you learn from years of boating, right?

View attachment 111869 View attachment 111870 View attachment 111872
Click to expand...
Thank you for the very helpful info. I will relay that info to the mechanic when the time comes to do it
 
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