Saildrive seawater cooling

[jgm]

The seawater engine cooling entry holes on my saildrive attract rapid mussel growth despite using the appropriate propodrev antifouling. Does the flow of seawater up the drive leg have any cooling impact on the drive mechanism? If not I intend to install a thru-hull cooling inlet pipe that bypasses the drive leg to ensure adequate flow. Any comments or advice welcome.

 

[Talbot]

why not do it as well as, rather than instead. Admitedly this would increase the number of holes in the bottom, but will provide the water through the leg as well as adequate supplies. It will also reduce the chance of getting a plastic bag stuck over the inlet!

 

[2Tizwoz]

In my experience mussels grow in through hull connections also. The saildrive leg does at least have multiple entries - slots each side and a hole in the bottom which considerably reduces the likelihood of all becoming blocked by weed or plastic.

 

[wizard]

Dont forget the water flows through the saildrive leg for a reason ie to cool the transmission.

The use of a separate inlet should only be considered as an emergency use only IMHO

 

[AIDY]

We changed our saildrive seal a few years ago, at the time we should of changed the seacock too. last year the seacock developed a leak so we decided to replace it.

It proved to be a difficult job due to the space we had in the engine bay. At the time i had a conversation with my Volvo Penta dealer on the other option i had if i could not get the sea cock out. He at the time suggested a seperate sea water pick up. He new a few boat that had gone down this route.

In the end i did not go down this route as i managed to get the seacock out okay.

I think the build up of rubbish in the pickup from the leg is a common thing I spend most years cleaning mine out with screw drivers and wire brushes.

If its a fouling problem, why not change the AF of the saildrive and prop. I use international trilux every year with sussess.

 

[oldsaltoz]

G'day Hardtack, and welcome to the YBW forums with your first post.

We have both out saildrives set up with their own thru' hull seawater pick ups, no problems at all and the filters thou very fine pick up very little.

The intakes are the large bronze ones with the open slots facing aft, it has been like this for 3 years now and no sign of high transmission temperatures.

Longest run was logged at 32.55 hours non stop at 2,600 rpm.

Avagoodweekend......

 

[spannerman]

There is a cooling water gallery around the base of the gearbox casting where the upper and lower halfs split, this is to provide cooling to the upper gearbox which doesn't benefit from being submersed as does the lower unit.

 

[jgm]

Many thanks to all for the helpful advice. I am not sure how critical the gearbox cooling aspect is. A shaft driven prop would not normally have water cooling at the gearbox. The arrangement I plan to make is to provide a suitably valved emergency cooling supply via a branch from the existing seawater flushing supply to the head. This will avoid the need for another hull penetration.

 

[spannerman]

Would just mention that you will need a shut off valve between the head and your new take-off otherwise there is the risk of the motor pulling air from the head and overheating, but I guess you have figured that one already.

 

[paddywackcocker]

On my own saildrive unit I have both leg and hull take ups, both always open never had any trouble. The cooling action of the oil and submersed caseing is more than enough to keep the transmission cool, as the oil gets circulated.