Stem Reinforcement on GRP Yacht?

[Jean-Dodd Van Clamme]

Hello - does anyone have experience reinforcing the stem and surrounding hull on a GRP yacht to protect against collision damage ? Or could point me towards any good write-ups? Im interested in thoughts on material (GRP/Kevlar/stainless sheet), thickness required to achieve meaningful improvement and technique and the potential pitfalls.

I am realistic that there will be a performance cost and there's a limit to how collision resistant a GRP boat is ever going to be but I would like to be able to nudge something slightly heavier than a crisp packet without mortal fear...

 

[Tranona]

Welcome to the forum.

Many modern boats use Kevlar in the bow sections. However, not sure why you think you need to reinforce the bow of an existing boat. Does your boat have a reputation of being weak in this area? Collision damage of that nature that results in foundering is very rare and I don't think I have ever seen any published articles on the subject - does not mean there are not any, but not mainstream.

However the materials you mention are the obvious ones, but access to extra layup internally may be an issue. Not sure how you would measure effectiveness other than if laid up properly thicker is normally stronger. Likewise not sure how you would measure any loss in performance except extra weight in the bows is usually not good.

 

[rotrax]

Judging by post collision pics, the stem normally does the damage if at right angles to the hit boat, often, in the case of power boats or performance yachts, cutting through the toerail and deck.

This leads me to believe your fear is pretty much unfounded.

However, hitting below the stem, under the forefoot, might be a different matter.

If you ARE concerned about a weakness in this area, consider a strong boat with a reputation for toughness.

My choice gives me confidence-a boat of the same make hit a Port Hand channel marker, a big one, after the skipper used it as a waypoint.

It was badly damaged around the stem, pulpit and bow, but hull integrity remained watertight.

The biggest damage was to the Skipper's reputation........................................

 

[scozzy]

All kinds of SS options online, maybe search "bow plate" rather than stem?

 

[dunedin]

As ever, insufficient information from the OP. What type / size etc of boat, what is the intended usage and what is the specific risk you are seeking to mitigate?
Somewhat different approaches and “thickness required” for a Leisure 17 vs an Oyster 885.

And collision damage risks may not be around the stem, which tends to be pretty strong. Collision with floating objects can cause issues with saildrives and/or rudders. Some boats with large hull windows could pose a bigger risk than the stemhead. And designed in waterproof collision bulkheads on some boats may be better than reinforcing stem - and stern.

 

[rogerthebodger]

I fitted a stainless capping to the bow of my boat not from a "crash production" but to prevent chipping of the paint on the bow of my steel boat.

You need to work out what you need to protect from just chipping of the gelcoat or from a major crash damage/ water ingress.

 

[William_H]

My little boat has a bronze fitting for the forestay which over laps the top of the bow and extends down 10 cms. it has prioved very effective at protecting the bow in a few collisions. Down from the top the stem has 2 through bolts for winching eye. The GRP right at the stem is remarkably thick. Bolts go through about 15mm of solid grp. Son assuming my little 21fter is representative of most boats then OP should not be concerned. If he is concerned re collision perhaps a water tight bulkhead back from the bow would avert too much water getting in from damage more likely on sides of bow and lower down.
Having said all that a fleet of 30 ft "Foundation" racing rental yachts here have great big lumps of rubber on bow for collisions with other boats and jetties. ol'will