How to dry catch humidity of inboard engine compartment

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Fmicol

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I'm bying a new boat fitted with an inboard Volvo engine and unfortunatly the engine with the temperature différences is always very humid 90 % causing rust problems,did somebody do have some experience how to dry the air Inside the engine compartment?

Fan or drying system?

Many thanks

François
 
A couple of tube heaters during the winter keep mine bone dry and not a problem in summer without any measures but I suppose it depends on the climate where your boat is and wether you have electricity on hand.
 
Your engine will need a lot of fresh air inlets to work properly, and this means damp air will always have access.

A rigorous paint regime for all metal parts is a start to prevent rust. If you use tube heaters in wintertime, you need to think about blocking the air inlets, but there is a lot to be said for keeping air flowing -unless your baot is in Sweden....
 
Firstly what model of boat and stern drive or shaft drive what model of engine.

In principle stop any rain water or seawater getting in to the engine compartment first.

if there has been salt water in the compartment wash out with fresh soapy water and dry off.

Check there are no leaks from the engine and rectify any.

If shaft drive stop leaks from stern seal or replace with Tides Marine seal.

After the above either a little bit of heat or a dehumidifier depending on layout of boat and engine.

My boat two 6.3 litre VP Diesels, Tides Marine Seals, no spray coming in air inlets, no leaks, and a dry bilge, a dehumidifier in the accommodation open to the engine room. Result no condensation ever and only external corrosion where salt water has leaked over engine from changing NPG impeller etc ..
 
Hi Francois,

a big problem in our Karnic is the salt water dripping from divers and their gear,
and draining in the bilge,
and being shaked around and splashing on the engines during navigation.
I assume you have exactly the same problem with your fishing activity’s.

we had severe corrosion on our VP D3's, and noticed how bad these 10yo lumps are made:
- galvanised steel screws, and hose clips, instead of stainless steel,...
- badly corroded alloy engine block,.
- Non salt resistant components such as the fuel priming pump, some pipes, risers, …

as suggested above by other posters,
imo the best solution is to rinse the engines after every use with fresh water,
and give them a yearly treatment with ACF50
or even better at the end and at the beginning of the season.
 
hello Bart,

you are right because of fishing washing with salt water i always have the problem,how did you rinse the engines after use?

I thought also specially in winter the engine compartment is very humide (air outside sometimes 90 %) and was thinking to open the compartment,heat or some device to low down humidity?

Many thanks
 
simonfraser said:
rinse with a hosepipe :)

ventilate and heat during the winter.
Click to expand...

exactly !

when its freezing, I place a old lo power heater inside the engine compartment
remember the Karnic is on a trailer, outside under a shed.

Francois, do you have freshwater and 230V power on the quay ?
 
Humidity can be kept at bay by simply keeping the air a few degrees above its dew point, so in Winter assume this is around 5oC so just keeping the engine bay around a rather cool 8oC will keep the bay and the rest of the boat dry and fresh. Also dry air doesn't need to circulate so much, as the purpose of airing is to dry the air naturally. so a small heater will achieve the desired result - no need to hold it at a centrally heated 20oC. Reducing as far as is easily achieved the openings will reduce the air change and hence heating effort (energy) required.

Salt is the enemy because it attracts moisture and is very corrosive when in solution, so every effort to keep the interior salt free is very worthwhile.
 
superheat6k said:
Humidity can be kept at bay by simply keeping the air a few degrees above its dew point, so in Winter assume this is around 5oC so just keeping the engine bay around a rather cool 8oC will keep the bay and the rest of the boat dry and fresh. Also dry air doesn't need to circulate so much, as the purpose of airing is to dry the air naturally. so a small heater will achieve the desired result - no need to hold it at a centrally heated 20oC. Reducing as far as is easily achieved the openings will reduce the air change and hence heating effort (energy) required.

Salt is the enemy because it attracts moisture and is very corrosive when in solution, so every effort to keep the interior salt free is very worthwhile.
Click to expand...

exactly,

rinsing with fresh water is the most important !,
and
F could place some length of " heating cable" in the engine compartment,
this type of cable is used to be placed along water pipes in places where it can freeze in winter,
we have these at home in our poolhouse
(very low power consumption, and water resistant)

just an example:
https://benl.rs-online.com/web/c/cables-wires/electrical-power-industrial-cable/trace-heating-cable/
 
If its just moisture you can get the silica absorbing packs, these absorb moisture and need drying out periodically, but may be useful in certain circumstances along with other measures.
 
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