noelex
Well-Known Member
If using aluminium backing plates, make sure you use marine grade aluminium, preferably one of the five series. 5083 is a good choice.
With marine grade aluminium saltwater will not be a problem, but water without any air will be. So the inside surface next to the hull needs to have a sealant that will prevent any water becoming trapped between the aluminium backing plate and the hull. Long term this is not always easy achieve given potentially high loads and consdering the difference in coefficients of expansion.
The outside surface of the aluminium will be fine if exposed to water (if it is marine grade). Trying to seal the outside surface (for example with paint) can be OK but there is once again a risk of water being trapped while air is excluded. So coatings on the outside, or trying to encapsulate the whole aluminium plate in fibreglass can be counterterproductive unless you can be sure of absolutely no moisture penetration.
Also try and isolate dissimilar metals such as stainless steel fastenings. Products such as Duralac and Tefgel are usually fine, but sometimes thin plastic or fibreglass inserts/washers can be helpful.
The above comments and precautions (with the exception of dissimilar metals) also apply to stainless steel backing plates to a certain extent. Both metals, but especially aluminium, do not do well when moisture is trapped and air is excluded. Attaching these metals to fibreglass or wood needs some care.
With marine grade aluminium saltwater will not be a problem, but water without any air will be. So the inside surface next to the hull needs to have a sealant that will prevent any water becoming trapped between the aluminium backing plate and the hull. Long term this is not always easy achieve given potentially high loads and consdering the difference in coefficients of expansion.
The outside surface of the aluminium will be fine if exposed to water (if it is marine grade). Trying to seal the outside surface (for example with paint) can be OK but there is once again a risk of water being trapped while air is excluded. So coatings on the outside, or trying to encapsulate the whole aluminium plate in fibreglass can be counterterproductive unless you can be sure of absolutely no moisture penetration.
Also try and isolate dissimilar metals such as stainless steel fastenings. Products such as Duralac and Tefgel are usually fine, but sometimes thin plastic or fibreglass inserts/washers can be helpful.
The above comments and precautions (with the exception of dissimilar metals) also apply to stainless steel backing plates to a certain extent. Both metals, but especially aluminium, do not do well when moisture is trapped and air is excluded. Attaching these metals to fibreglass or wood needs some care.
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Surely we have better things to do than argue over which is best Wooden vs Plastic chopping boards!
Makes you wonder how people survived through the era of wood chopping boards!