I'm adding a bilge pump on my Mac 25 right next to the cable entrance for the swing keel. I drilled the exit hole high on the transom next to the backstay anchor plate. My question is does drilling a 1 inch whole weaken the transom structure? The bilge hose will be about 10 feet. Any suggestions? Mac
Drilling through the transom
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What I think
I guess that I am just like everyone else when I say that I have my own opinion. Whether it is right or not is up to you. As far as drilling a 1" hole in your boat weakening it, I think that it does. However, with the replacement of a round plastic object inserted into the hole, you have reinforced that void, thus gaining atleast the original integrity of the structure. I just installed a bilge pump in my Mac25 and ran the tubing through the rear of the boat. My worries are that I have 15' of tubing for a bilge pump to pump the water out and that the pump will not have enough power to expell the water. Anyway best of luck! Justin Gaines
I guess that I am just like everyone else when I say that I have my own opinion. Whether it is right or not is up to you. As far as drilling a 1" hole in your boat weakening it, I think that it does. However, with the replacement of a round plastic object inserted into the hole, you have reinforced that void, thus gaining atleast the original integrity of the structure. I just installed a bilge pump in my Mac25 and ran the tubing through the rear of the boat. My worries are that I have 15' of tubing for a bilge pump to pump the water out and that the pump will not have enough power to expell the water. Anyway best of luck! Justin Gaines
Bilge Question
I just installed a bilge as well, and based on advice on this site, I chose not to make another hole in the transom. Instead I connected my bilge hose to the cabin drain. I have only had it out twice, but it works great. If you already made the hole, I can tell you after doing fibreglass reinforcement to the transom and having had a good opportunity to see how well these boats are built, I dont think a one inch hole is going to make a lot of difference.
I just installed a bilge as well, and based on advice on this site, I chose not to make another hole in the transom. Instead I connected my bilge hose to the cabin drain. I have only had it out twice, but it works great. If you already made the hole, I can tell you after doing fibreglass reinforcement to the transom and having had a good opportunity to see how well these boats are built, I dont think a one inch hole is going to make a lot of difference.
No Problem
Given the total surface area of the transom, 1" isn't significant, unless it's close to your rudder pintles or motor mount, make sure it's 6" or further from either of those points. The collar on the plastic through hulls, if epoxied in place will assure there is no loss in structural integrity. My bilge pump was already installed when I got my boat, I assumed they were installed at the factory. Mine uses sch. 40 PVC and clear hose and runs slightly downhill to the discharge which is above the cockpit drain about 12" or so. It sounds as if the hole is already drilled so sort of makes it a moot point, eh?
Given the total surface area of the transom, 1" isn't significant, unless it's close to your rudder pintles or motor mount, make sure it's 6" or further from either of those points. The collar on the plastic through hulls, if epoxied in place will assure there is no loss in structural integrity. My bilge pump was already installed when I got my boat, I assumed they were installed at the factory. Mine uses sch. 40 PVC and clear hose and runs slightly downhill to the discharge which is above the cockpit drain about 12" or so. It sounds as if the hole is already drilled so sort of makes it a moot point, eh?
my .02
I used to design floor beams for Boeing in a previous life. I nice clean hole usually prevented cracking as opposed to angular cuts. However, they weakened the beam. We would rivet on hole doublers or flange the holes in the web for strength depending on the loads. In this situation I don't think it weakens the structure. I would be more concerned (not really) about the proximity of the hole to others. If there is a lot of vibration from a motor eg, a crack might xfer from one hole to another. In other words, Abby Normal's suggestions are right on.
I used to design floor beams for Boeing in a previous life. I nice clean hole usually prevented cracking as opposed to angular cuts. However, they weakened the beam. We would rivet on hole doublers or flange the holes in the web for strength depending on the loads. In this situation I don't think it weakens the structure. I would be more concerned (not really) about the proximity of the hole to others. If there is a lot of vibration from a motor eg, a crack might xfer from one hole to another. In other words, Abby Normal's suggestions are right on.
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